diff --git a/neo.UnitTests/Ledger/UT_ContractState.cs b/neo.UnitTests/Ledger/UT_ContractState.cs
index 87f1d7ac88..097e9c3e04 100644
--- a/neo.UnitTests/Ledger/UT_ContractState.cs
+++ b/neo.UnitTests/Ledger/UT_ContractState.cs
@@ -1,4 +1,4 @@
-using FluentAssertions;
+using FluentAssertions;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Neo.IO;
 using Neo.IO.Json;
@@ -92,7 +92,7 @@ public void TestToJson()
         {
             JObject json = contract.ToJson();
             json["hash"].AsString().Should().Be("0x820944cfdc70976602d71b0091445eedbc661bc5");
-            json["script"].AsString().Should().Be("01");
+            json["script"].AsString().Should().Be("AQ==");
             json["manifest"].AsString().Should().Be(manifest.ToJson().AsString());
         }
     }
diff --git a/neo.UnitTests/Network/P2P/Payloads/UT_Block.cs b/neo.UnitTests/Network/P2P/Payloads/UT_Block.cs
index f27421dd74..a26741c732 100644
--- a/neo.UnitTests/Network/P2P/Payloads/UT_Block.cs
+++ b/neo.UnitTests/Network/P2P/Payloads/UT_Block.cs
@@ -210,7 +210,7 @@ public void ToJson()
 
             JObject scObj = ((JArray)jObj["witnesses"])[0];
             scObj["invocation"].AsString().Should().Be("");
-            scObj["verification"].AsString().Should().Be("51");
+            scObj["verification"].AsString().Should().Be("UQ==");
 
             jObj["tx"].Should().NotBeNull();
             JArray txObj = (JArray)jObj["tx"];
diff --git a/neo.UnitTests/Network/P2P/Payloads/UT_Transaction.cs b/neo.UnitTests/Network/P2P/Payloads/UT_Transaction.cs
index d52867e99e..217e207f83 100644
--- a/neo.UnitTests/Network/P2P/Payloads/UT_Transaction.cs
+++ b/neo.UnitTests/Network/P2P/Payloads/UT_Transaction.cs
@@ -1093,7 +1093,7 @@ public void ToJson()
             ((JArray)jObj["attributes"]).Count.Should().Be(0);
             ((JArray)jObj["cosigners"]).Count.Should().Be(0);
             jObj["net_fee"].AsString().Should().Be("0");
-            jObj["script"].AsString().Should().Be("4220202020202020202020202020202020202020202020202020202020202020");
+            jObj["script"].AsString().Should().Be("QiAgICAgICAgICAgICAgICAgICAgICAgICAgICAgICA=");
             jObj["sys_fee"].AsString().Should().Be("4200000000");
         }
     }
diff --git a/neo.UnitTests/Network/P2P/Payloads/UT_Witness.cs b/neo.UnitTests/Network/P2P/Payloads/UT_Witness.cs
index 1ef1e2d120..502317e604 100644
--- a/neo.UnitTests/Network/P2P/Payloads/UT_Witness.cs
+++ b/neo.UnitTests/Network/P2P/Payloads/UT_Witness.cs
@@ -146,8 +146,8 @@ public void ToJson()
             JObject json = uut.ToJson();
             Assert.IsTrue(json.ContainsProperty("invocation"));
             Assert.IsTrue(json.ContainsProperty("verification"));
-            Assert.AreEqual(json["invocation"].AsString(), "2020");
-            Assert.AreEqual(json["verification"].AsString(), "202020");
+            Assert.AreEqual(json["invocation"].AsString(), "ICA=");
+            Assert.AreEqual(json["verification"].AsString(), "ICAg");
         }
     }
 }
diff --git a/neo.UnitTests/Network/RPC/Models/UT_RpcNep5Balance.cs b/neo.UnitTests/Network/RPC/Models/UT_RpcNep5Balance.cs
index ee32c1998e..9131db811a 100644
--- a/neo.UnitTests/Network/RPC/Models/UT_RpcNep5Balance.cs
+++ b/neo.UnitTests/Network/RPC/Models/UT_RpcNep5Balance.cs
@@ -45,7 +45,7 @@ public void TestToJson()
             balance.Amount = BigInteger.Zero;
             balance.LastUpdatedBlock = 0;
             var json = balance.ToJson();
-            json["asset_hash"].AsString().Should().Be("0000000000000000000000000000000000000000");
+            json["asset_hash"].AsString().Should().Be("0x0000000000000000000000000000000000000000");
             json["amount"].AsNumber().Should().Be(0);
             json["last_updated_block"].AsNumber().Should().Be(0);
         }
@@ -54,7 +54,7 @@ public void TestToJson()
         public void TestFromJson()
         {
             var json = new JObject();
-            json["asset_hash"] = "0000000000000000000000000000000000000000";
+            json["asset_hash"] = "0x0000000000000000000000000000000000000000";
             json["amount"] = "0";
             json["last_updated_block"] = "0";
             var rpcNep5Balance = RpcNep5Balance.FromJson(json);
diff --git a/neo.UnitTests/SmartContract/Manifest/UT_ContractManifest.cs b/neo.UnitTests/SmartContract/Manifest/UT_ContractManifest.cs
index 910f30b019..5c2a99ff56 100644
--- a/neo.UnitTests/SmartContract/Manifest/UT_ContractManifest.cs
+++ b/neo.UnitTests/SmartContract/Manifest/UT_ContractManifest.cs
@@ -77,7 +77,7 @@ public void ParseFromJson_Trust()
         [TestMethod]
         public void ParseFromJson_Groups()
         {
-            var json = @"{""groups"":[{""pubKey"":""03b209fd4f53a7170ea4444e0cb0a6bb6a53c2bd016926989cf85f9b0fba17a70c"",""signature"":""41414141414141414141414141414141414141414141414141414141414141414141414141414141414141414141414141414141414141414141414141414141""}],""features"":{""storage"":false,""payable"":false},""abi"":{""hash"":""0x0000000000000000000000000000000000000000"",""entryPoint"":{""name"":""Main"",""parameters"":[{""name"":""operation"",""type"":""String""},{""name"":""args"",""type"":""Array""}],""returnType"":""Any""},""methods"":[],""events"":[]},""permissions"":[{""contract"":""*"",""methods"":""*""}],""trusts"":[],""safeMethods"":[]}";
+            var json = @"{""groups"":[{""pubKey"":""03b209fd4f53a7170ea4444e0cb0a6bb6a53c2bd016926989cf85f9b0fba17a70c"",""signature"":""QUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQUFBQQ==""}],""features"":{""storage"":false,""payable"":false},""abi"":{""hash"":""0x0000000000000000000000000000000000000000"",""entryPoint"":{""name"":""Main"",""parameters"":[{""name"":""operation"",""type"":""String""},{""name"":""args"",""type"":""Array""}],""returnType"":""Any""},""methods"":[],""events"":[]},""permissions"":[{""contract"":""*"",""methods"":""*""}],""trusts"":[],""safeMethods"":[]}";
             var manifest = ContractManifest.Parse(json);
             Assert.AreEqual(manifest.ToString(), json);
 
diff --git a/neo.UnitTests/SmartContract/UT_ContractParameterContext.cs b/neo.UnitTests/SmartContract/UT_ContractParameterContext.cs
index 0b06260b24..0e035349d1 100644
--- a/neo.UnitTests/SmartContract/UT_ContractParameterContext.cs
+++ b/neo.UnitTests/SmartContract/UT_ContractParameterContext.cs
@@ -1,4 +1,4 @@
-using FluentAssertions;
+using FluentAssertions;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Neo.Cryptography.ECC;
 using Neo.Network.P2P.Payloads;
@@ -46,13 +46,13 @@ public void TestToString()
             var context = new ContractParametersContext(tx);
             context.Add(contract, 0, new byte[] { 0x01 });
             string str = context.ToString();
-            str.Should().Be("{\"type\":\"Neo.Network.P2P.Payloads.Transaction\",\"hex\":\"0000000000f277f1144035a43897f9fa115258eac015adcabe000000000000000000000000000000000000000000000100\",\"items\":{\"0xbecaad15c0ea585211faf99738a4354014f177f2\":{\"script\":\"21026ff03b949241ce1dadd43519e6960e0a85b41a69a05c328103aa2bce1594ca1668747476aa\",\"parameters\":[{\"type\":\"Signature\",\"value\":\"01\"}]}}}");
+            str.Should().Be("{\"type\":\"Neo.Network.P2P.Payloads.Transaction\",\"hex\":\"AAAAAADyd\\/EUQDWkOJf5\\u002BhFSWOrAFa3KvgAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAA==\",\"items\":{\"0xbecaad15c0ea585211faf99738a4354014f177f2\":{\"script\":\"IQJv8DuUkkHOHa3UNRnmlg4KhbQaaaBcMoEDqivOFZTKFmh0dHaq\",\"parameters\":[{\"type\":\"Signature\",\"value\":\"AQ==\"}]}}}");
         }
 
         [TestMethod]
         public void TestParse()
         {
-            var ret = ContractParametersContext.Parse("{\"type\":\"Neo.Network.P2P.Payloads.Transaction\",\"hex\":\"0000000000f277f1144035a43897f9fa115258eac015adcabe000000000000000000000000000000000000000000000100\",\"items\":{\"0xbecaad15c0ea585211faf99738a4354014f177f2\":{\"script\":\"21026ff03b949241ce1dadd43519e6960e0a85b41a69a05c328103aa2bce1594ca1668747476aa\",\"parameters\":[{\"type\":\"Signature\",\"value\":\"01\"}]}}}");
+            var ret = ContractParametersContext.Parse("{\"type\":\"Neo.Network.P2P.Payloads.Transaction\",\"hex\":\"AAAAAADyd\\/EUQDWkOJf5\\u002BhFSWOrAFa3KvgAAAAAAAAAAAAAAAAAAAAAAAAAAAAABAA==\",\"items\":{\"0xbecaad15c0ea585211faf99738a4354014f177f2\":{\"script\":\"IQJv8DuUkkHOHa3UNRnmlg4KhbQaaaBcMoEDqivOFZTKFmh0dHaq\",\"parameters\":[{\"type\":\"Signature\",\"value\":\"AQ==\"}]}}}");
             ret.ScriptHashes[0].ToString().Should().Be("0xbecaad15c0ea585211faf99738a4354014f177f2");
             ((Transaction)ret.Verifiable).Script.ToHexString().Should().Be(new byte[1].ToHexString());
         }
diff --git a/neo.UnitTests/SmartContract/UT_JsonSerializer.cs b/neo.UnitTests/SmartContract/UT_JsonSerializer.cs
index 9863d72b0d..ed9c9cd72b 100644
--- a/neo.UnitTests/SmartContract/UT_JsonSerializer.cs
+++ b/neo.UnitTests/SmartContract/UT_JsonSerializer.cs
@@ -268,7 +268,7 @@ public void Serialize_Array_Bool_Str_Num()
 
             var json = JsonSerializer.Serialize(entry).ToString();
 
-            Assert.AreEqual(json, "[true,\"74657374\",123]");
+            Assert.AreEqual(json, "[true,\"dGVzdA==\",123]");
         }
 
         [TestMethod]
@@ -297,7 +297,7 @@ public void Serialize_Array_OfArray()
 
             var json = JsonSerializer.Serialize(entry).ToString();
 
-            Assert.AreEqual(json, "[[true,\"7465737431\",123],[true,\"7465737432\",321]]");
+            Assert.AreEqual(json, "[[true,\"dGVzdDE=\",123],[true,\"dGVzdDI=\",321]]");
         }
 
         [TestMethod]
diff --git a/neo.UnitTests/SmartContract/UT_Syscalls.cs b/neo.UnitTests/SmartContract/UT_Syscalls.cs
index d24850de40..b778f63d94 100644
--- a/neo.UnitTests/SmartContract/UT_Syscalls.cs
+++ b/neo.UnitTests/SmartContract/UT_Syscalls.cs
@@ -76,7 +76,7 @@ public void System_Blockchain_GetBlock()
                 Assert.AreEqual(1, engine.ResultStack.Count);
                 Assert.IsInstanceOfType(engine.ResultStack.Peek(), typeof(ByteArray));
                 Assert.AreEqual(engine.ResultStack.Pop().GetByteArray().ToHexString(),
-                    "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");
+                    "5b22556168355c2f4b6f446d39723064555950636353714346745a30594f726b583164646e7334366e676e3962383d222c332c22414141414141414141414141414141414141414141414141414141414141414141414141414141414141413d222c22414141414141414141414141414141414141414141414141414141414141414141414141414141414141413d222c322c312c224141414141414141414141414141414141414141414141414141413d222c315d");
                 Assert.AreEqual(0, engine.ResultStack.Count);
 
                 // Clean
@@ -127,7 +127,7 @@ public void System_ExecutionEngine_GetScriptContainer()
                 Assert.AreEqual(1, engine.ResultStack.Count);
                 Assert.IsInstanceOfType(engine.ResultStack.Peek(), typeof(ByteArray));
                 Assert.AreEqual(engine.ResultStack.Pop().GetByteArray().ToHexString(),
-                    @"5b2266613434383036313834373332636138613136363037356430306133643861326531353462333337313333333138303336356561643732373561663132666264222c362c342c2266666666666666666666666666666666666666666666666666666666666666666666666666666666222c332c322c352c223031225d");
+                    @"5b225c75303032426b53415959527a4c4b69685a676464414b50596f754655737a63544d7867445a6572584a3172784c37303d222c362c342c225c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f5c2f383d222c332c322c352c2241513d3d225d");
                 Assert.AreEqual(0, engine.ResultStack.Count);
             }
         }
diff --git a/neo.UnitTests/Wallets/NEP6/UT_NEP6Account.cs b/neo.UnitTests/Wallets/NEP6/UT_NEP6Account.cs
index ed84b1bad3..0477b8a595 100644
--- a/neo.UnitTests/Wallets/NEP6/UT_NEP6Account.cs
+++ b/neo.UnitTests/Wallets/NEP6/UT_NEP6Account.cs
@@ -104,7 +104,7 @@ public void TestGetKeyWithString()
         public void TestToJson()
         {
             JObject nep6contract = new JObject();
-            nep6contract["script"] = "2103603f3880eb7aea0ad4500893925e4a42fea48a44ee6f898a10b3c7ce05d2a267ac";
+            nep6contract["script"] = "IQNgPziA63rqCtRQCJOSXkpC/qSKRO5viYoQs8fOBdKiZ6w=";
             JObject parameters = new JObject();
             parameters["type"] = 0x00;
             parameters["name"] = "Sig";
@@ -121,7 +121,7 @@ public void TestToJson()
             json["isDefault"].ToString().Should().Be("false");
             json["lock"].ToString().Should().Be("false");
             json["key"].Should().BeNull();
-            json["contract"]["script"].ToString().Should().Be("\"2103603f3880eb7aea0ad4500893925e4a42fea48a44ee6f898a10b3c7ce05d2a267ac\"");
+            json["contract"]["script"].ToString().Should().Be("\"IQNgPziA63rqCtRQCJOSXkpC\\/qSKRO5viYoQs8fOBdKiZ6w=\"");
             json["extra"].Should().BeNull();
 
             _account.Contract = null;
diff --git a/neo.UnitTests/Wallets/NEP6/UT_NEP6Contract.cs b/neo.UnitTests/Wallets/NEP6/UT_NEP6Contract.cs
index 3f4e7b3a63..1594672946 100644
--- a/neo.UnitTests/Wallets/NEP6/UT_NEP6Contract.cs
+++ b/neo.UnitTests/Wallets/NEP6/UT_NEP6Contract.cs
@@ -3,6 +3,7 @@
 using Neo.IO.Json;
 using Neo.SmartContract;
 using Neo.Wallets.NEP6;
+using System;
 
 namespace Neo.UnitTests.Wallets.NEP6
 {
@@ -19,7 +20,7 @@ public void TestFromNullJson()
         [TestMethod]
         public void TestFromJson()
         {
-            string json = "{\"script\":\"2103ef891df4c0b7eefb937d21ea0fb88cde8e0d82a7ff11872b5e7047969dafb4eb68747476aa\"," +
+            string json = "{\"script\":\"IQPviR30wLfu+5N9IeoPuIzejg2Cp/8RhytecEeWna+062h0dHaq\"," +
                 "\"parameters\":[{\"name\":\"signature\",\"type\":\"Signature\"}],\"deployed\":false}";
             JObject @object = JObject.Parse(json);
 
@@ -45,7 +46,7 @@ public void TestToJson()
 
             JObject @object = nep6Contract.ToJson();
             JString jString = (JString)@object["script"];
-            jString.Value.Should().Be(nep6Contract.Script.ToHexString());
+            jString.Value.Should().Be(Convert.ToBase64String(nep6Contract.Script, Base64FormattingOptions.None));
 
             JBoolean jBoolean = (JBoolean)@object["deployed"];
             jBoolean.Value.Should().BeFalse();
diff --git a/neo/Ledger/ContractState.cs b/neo/Ledger/ContractState.cs
index c369e5d59f..ea1860668e 100644
--- a/neo/Ledger/ContractState.cs
+++ b/neo/Ledger/ContractState.cs
@@ -4,6 +4,7 @@
 using Neo.SmartContract.Manifest;
 using Neo.VM;
 using Neo.VM.Types;
+using System;
 using System.IO;
 
 namespace Neo.Ledger
@@ -62,7 +63,7 @@ public JObject ToJson()
         {
             JObject json = new JObject();
             json["hash"] = ScriptHash.ToString();
-            json["script"] = Script.ToHexString();
+            json["script"] = Convert.ToBase64String(Script);
             json["manifest"] = Manifest.ToJson();
             return json;
         }
@@ -70,7 +71,7 @@ public JObject ToJson()
         public static ContractState FromJson(JObject json)
         {
             ContractState contractState = new ContractState();
-            contractState.Script = json["script"].AsString().HexToBytes();
+            contractState.Script = Convert.FromBase64String(json["script"].AsString());
             contractState.Manifest = ContractManifest.FromJson(json["manifest"]);
             return contractState;
         }
@@ -82,8 +83,8 @@ public StackItem ToStackItem()
                new StackItem[]
                {
                     new ByteArray(Script),
-                    new Boolean(HasStorage),
-                    new Boolean(Payable),
+                    new VM.Types.Boolean(HasStorage),
+                    new VM.Types.Boolean(Payable),
                }
            );
         }
diff --git a/neo/Network/P2P/Payloads/Transaction.cs b/neo/Network/P2P/Payloads/Transaction.cs
index af38ef6dcc..c135185272 100644
--- a/neo/Network/P2P/Payloads/Transaction.cs
+++ b/neo/Network/P2P/Payloads/Transaction.cs
@@ -183,7 +183,7 @@ public JObject ToJson()
             json["valid_until_block"] = ValidUntilBlock;
             json["attributes"] = Attributes.Select(p => p.ToJson()).ToArray();
             json["cosigners"] = Cosigners.Select(p => p.ToJson()).ToArray();
-            json["script"] = Script.ToHexString();
+            json["script"] = Convert.ToBase64String(Script);
             json["witnesses"] = Witnesses.Select(p => p.ToJson()).ToArray();
             return json;
         }
@@ -199,7 +199,7 @@ public static Transaction FromJson(JObject json)
             tx.ValidUntilBlock = uint.Parse(json["valid_until_block"].AsString());
             tx.Attributes = ((JArray)json["attributes"]).Select(p => TransactionAttribute.FromJson(p)).ToArray();
             tx.Cosigners = ((JArray)json["cosigners"]).Select(p => Cosigner.FromJson(p)).ToArray();
-            tx.Script = json["script"].AsString().HexToBytes();
+            tx.Script = Convert.FromBase64String(json["script"].AsString());
             tx.Witnesses = ((JArray)json["witnesses"]).Select(p => Witness.FromJson(p)).ToArray();
             return tx;
         }
diff --git a/neo/Network/P2P/Payloads/TransactionAttribute.cs b/neo/Network/P2P/Payloads/TransactionAttribute.cs
index 5adc34db8e..fa92010004 100644
--- a/neo/Network/P2P/Payloads/TransactionAttribute.cs
+++ b/neo/Network/P2P/Payloads/TransactionAttribute.cs
@@ -30,7 +30,7 @@ public JObject ToJson()
         {
             JObject json = new JObject();
             json["usage"] = Usage;
-            json["data"] = Data.ToHexString();
+            json["data"] = Convert.ToBase64String(Data);
             return json;
         }
 
@@ -38,7 +38,7 @@ public static TransactionAttribute FromJson(JObject json)
         {
             TransactionAttribute transactionAttribute = new TransactionAttribute();
             transactionAttribute.Usage = (TransactionAttributeUsage)(byte.Parse(json["usage"].AsString()));
-            transactionAttribute.Data = json["data"].AsString().HexToBytes();
+            transactionAttribute.Data = Convert.FromBase64String(json["data"].AsString());
             return transactionAttribute;
         }
     }
diff --git a/neo/Network/P2P/Payloads/Witness.cs b/neo/Network/P2P/Payloads/Witness.cs
index 227d810a39..55ba4f2564 100644
--- a/neo/Network/P2P/Payloads/Witness.cs
+++ b/neo/Network/P2P/Payloads/Witness.cs
@@ -1,7 +1,7 @@
 using Neo.IO;
 using Neo.IO.Json;
 using Neo.SmartContract;
-using Neo.VM;
+using System;
 using System.IO;
 
 namespace Neo.Network.P2P.Payloads
@@ -44,16 +44,16 @@ void ISerializable.Serialize(BinaryWriter writer)
         public JObject ToJson()
         {
             JObject json = new JObject();
-            json["invocation"] = InvocationScript.ToHexString();
-            json["verification"] = VerificationScript.ToHexString();
+            json["invocation"] = Convert.ToBase64String(InvocationScript);
+            json["verification"] = Convert.ToBase64String(VerificationScript);
             return json;
         }
 
         public static Witness FromJson(JObject json)
         {
             Witness witness = new Witness();
-            witness.InvocationScript = json["invocation"].AsString().HexToBytes();
-            witness.VerificationScript = json["verification"].AsString().HexToBytes();
+            witness.InvocationScript = Convert.FromBase64String(json["invocation"].AsString());
+            witness.VerificationScript = Convert.FromBase64String(json["verification"].AsString());
             return witness;
         }
     }
diff --git a/neo/Network/RPC/Models/RpcNep5Balances.cs b/neo/Network/RPC/Models/RpcNep5Balances.cs
index b471ab4545..74fe7be729 100644
--- a/neo/Network/RPC/Models/RpcNep5Balances.cs
+++ b/neo/Network/RPC/Models/RpcNep5Balances.cs
@@ -39,7 +39,7 @@ public class RpcNep5Balance
         public JObject ToJson()
         {
             JObject json = new JObject();
-            json["asset_hash"] = AssetHash.ToArray().ToHexString();
+            json["asset_hash"] = AssetHash.ToString();
             json["amount"] = Amount.ToString();
             json["last_updated_block"] = LastUpdatedBlock.ToString();
             return json;
diff --git a/neo/SmartContract/ContractParameter.cs b/neo/SmartContract/ContractParameter.cs
index cae59229b8..5cdc520808 100644
--- a/neo/SmartContract/ContractParameter.cs
+++ b/neo/SmartContract/ContractParameter.cs
@@ -66,7 +66,7 @@ public static ContractParameter FromJson(JObject json)
                 {
                     case ContractParameterType.Signature:
                     case ContractParameterType.ByteArray:
-                        parameter.Value = json["value"].AsString().HexToBytes();
+                        parameter.Value = Convert.FromBase64String(json["value"].AsString());
                         break;
                     case ContractParameterType.Boolean:
                         parameter.Value = json["value"].AsBoolean();
@@ -147,7 +147,7 @@ private static JObject ToJson(ContractParameter parameter, HashSet<ContractParam
                 {
                     case ContractParameterType.Signature:
                     case ContractParameterType.ByteArray:
-                        json["value"] = ((byte[])parameter.Value).ToHexString();
+                        json["value"] = Convert.ToBase64String((byte[])parameter.Value);
                         break;
                     case ContractParameterType.Boolean:
                         json["value"] = (bool)parameter.Value;
diff --git a/neo/SmartContract/ContractParametersContext.cs b/neo/SmartContract/ContractParametersContext.cs
index 0388df342c..327c8b1ef8 100644
--- a/neo/SmartContract/ContractParametersContext.cs
+++ b/neo/SmartContract/ContractParametersContext.cs
@@ -33,12 +33,12 @@ public static ContextItem FromJson(JObject json)
             {
                 return new ContextItem
                 {
-                    Script = json["script"]?.AsString().HexToBytes(),
+                    Script = Convert.FromBase64String(json["script"]?.AsString()),
                     Parameters = ((JArray)json["parameters"]).Select(p => ContractParameter.FromJson(p)).ToArray(),
                     Signatures = json["signatures"]?.Properties.Select(p => new
                     {
                         PublicKey = ECPoint.Parse(p.Key, ECCurve.Secp256r1),
-                        Signature = p.Value.AsString().HexToBytes()
+                        Signature = Convert.FromBase64String(p.Value.AsString())
                     }).ToDictionary(p => p.PublicKey, p => p.Signature)
                 };
             }
@@ -47,13 +47,13 @@ public JObject ToJson()
             {
                 JObject json = new JObject();
                 if (Script != null)
-                    json["script"] = Script.ToHexString();
+                    json["script"] = Convert.ToBase64String(Script);
                 json["parameters"] = new JArray(Parameters.Select(p => p.ToJson()));
                 if (Signatures != null)
                 {
                     json["signatures"] = new JObject();
                     foreach (var signature in Signatures)
-                        json["signatures"][signature.Key.ToString()] = signature.Value.ToHexString();
+                        json["signatures"][signature.Key.ToString()] = Convert.ToBase64String(signature.Value);
                 }
                 return json;
             }
@@ -215,7 +215,7 @@ public static ContractParametersContext FromJson(JObject json)
             if (!typeof(IVerifiable).IsAssignableFrom(type)) throw new FormatException();
 
             var verifiable = (IVerifiable)Activator.CreateInstance(type);
-            using (MemoryStream ms = new MemoryStream(json["hex"].AsString().HexToBytes(), false))
+            using (MemoryStream ms = new MemoryStream(Convert.FromBase64String(json["hex"].AsString()), false))
             using (BinaryReader reader = new BinaryReader(ms, Encoding.UTF8))
             {
                 verifiable.DeserializeUnsigned(reader);
@@ -284,7 +284,7 @@ public JObject ToJson()
             {
                 Verifiable.SerializeUnsigned(writer);
                 writer.Flush();
-                json["hex"] = ms.ToArray().ToHexString();
+                json["hex"] = Convert.ToBase64String(ms.ToArray());
             }
             json["items"] = new JObject();
             foreach (var item in ContextItems)
diff --git a/neo/SmartContract/JsonSerializer.cs b/neo/SmartContract/JsonSerializer.cs
index 030585420e..96c525e0b1 100644
--- a/neo/SmartContract/JsonSerializer.cs
+++ b/neo/SmartContract/JsonSerializer.cs
@@ -26,7 +26,7 @@ public static JObject Serialize(StackItem item)
                     }
                 case ByteArray buffer:
                     {
-                        return buffer.GetByteArray().ToHexString();
+                        return Convert.ToBase64String(buffer.GetByteArray());
                     }
                 case Integer num:
                     {
diff --git a/neo/SmartContract/Manifest/ContractGroup.cs b/neo/SmartContract/Manifest/ContractGroup.cs
index 75359e782a..249c6b8a53 100644
--- a/neo/SmartContract/Manifest/ContractGroup.cs
+++ b/neo/SmartContract/Manifest/ContractGroup.cs
@@ -1,6 +1,7 @@
 using Neo.Cryptography;
 using Neo.Cryptography.ECC;
 using Neo.IO.Json;
+using System;
 
 namespace Neo.SmartContract.Manifest
 {
@@ -30,7 +31,7 @@ public static ContractGroup FromJson(JObject json)
             return new ContractGroup
             {
                 PubKey = ECPoint.Parse(json["pubKey"].AsString(), ECCurve.Secp256r1),
-                Signature = json["signature"].AsString().HexToBytes(),
+                Signature = Convert.FromBase64String(json["signature"].AsString()),
             };
         }
 
@@ -48,7 +49,7 @@ public virtual JObject ToJson()
         {
             var json = new JObject();
             json["pubKey"] = PubKey.ToString();
-            json["signature"] = Signature.ToHexString();
+            json["signature"] = Convert.ToBase64String(Signature);
             return json;
         }
     }
diff --git a/neo/Wallets/NEP6/NEP6Contract.cs b/neo/Wallets/NEP6/NEP6Contract.cs
index 45f0b5e157..af27db6c4c 100644
--- a/neo/Wallets/NEP6/NEP6Contract.cs
+++ b/neo/Wallets/NEP6/NEP6Contract.cs
@@ -1,5 +1,6 @@
 using Neo.IO.Json;
 using Neo.SmartContract;
+using System;
 using System.Linq;
 
 namespace Neo.Wallets.NEP6
@@ -14,7 +15,7 @@ public static NEP6Contract FromJson(JObject json)
             if (json == null) return null;
             return new NEP6Contract
             {
-                Script = json["script"].AsString().HexToBytes(),
+                Script = Convert.FromBase64String(json["script"].AsString()),
                 ParameterList = ((JArray)json["parameters"]).Select(p => p["type"].TryGetEnum<ContractParameterType>()).ToArray(),
                 ParameterNames = ((JArray)json["parameters"]).Select(p => p["name"].AsString()).ToArray(),
                 Deployed = json["deployed"].AsBoolean()
@@ -24,7 +25,7 @@ public static NEP6Contract FromJson(JObject json)
         public JObject ToJson()
         {
             JObject contract = new JObject();
-            contract["script"] = Script.ToHexString();
+            contract["script"] = Convert.ToBase64String(Script);
             contract["parameters"] = new JArray(ParameterList.Zip(ParameterNames, (type, name) =>
             {
                 JObject parameter = new JObject();