diff --git a/setup.py b/setup.py
index 950aea67..95e041ec 100644
--- a/setup.py
+++ b/setup.py
@@ -7,7 +7,7 @@
 TESTS_REQUIRES = [
     'flake8',
     'pytest==7.0.1',
-    'pytest-mock>=3.5.1',
+    'pytest-mock==3.13.0',
     'coverage==6.2',
     'pytest-cov',
     'importlib-metadata==4.2',
diff --git a/splitio/api/client.py b/splitio/api/client.py
index c58d14e9..073970fc 100644
--- a/splitio/api/client.py
+++ b/splitio/api/client.py
@@ -28,10 +28,12 @@ class HttpClient(object):
     AUTH_URL = 'https://auth.split.io/api'
     TELEMETRY_URL = 'https://telemetry.split.io/api'
 
-    def __init__(self, timeout=None, sdk_url=None, events_url=None, auth_url=None, telemetry_url=None):
+    def __init__(self, request_decorator, timeout=None, sdk_url=None, events_url=None, auth_url=None, telemetry_url=None):
         """
         Class constructor.
 
+        :param request_decorator: RequestDecorator instance
+        :type request_decorator: splitio.api.request_decorator.RequestDecorator
         :param timeout: How many milliseconds to wait until the server responds.
         :type timeout: int
         :param sdk_url: Optional alternative sdk URL.
@@ -50,6 +52,7 @@ def __init__(self, timeout=None, sdk_url=None, events_url=None, auth_url=None, t
             'auth': auth_url if auth_url is not None else self.AUTH_URL,
             'telemetry': telemetry_url if telemetry_url is not None else self.TELEMETRY_URL,
         }
+        self._request_decorator = request_decorator
 
     def _build_url(self, server, path):
         """
@@ -101,7 +104,9 @@ def get(self, server, path, sdk_key, query=None, extra_headers=None):  # pylint:
             headers.update(extra_headers)
 
         try:
-            response = requests.get(
+            session = requests.Session()
+            session = self._request_decorator.decorate_headers(session)
+            response = session.get(
                 self._build_url(server, path),
                 params=query,
                 headers=headers,
@@ -110,6 +115,8 @@ def get(self, server, path, sdk_key, query=None, extra_headers=None):  # pylint:
             return HttpResponse(response.status_code, response.text)
         except Exception as exc:  # pylint: disable=broad-except
             raise HttpClientException('requests library is throwing exceptions') from exc
+        finally:
+            session.close()
 
     def post(self, server, path, sdk_key, body, query=None, extra_headers=None):  # pylint: disable=too-many-arguments
         """
@@ -137,7 +144,9 @@ def post(self, server, path, sdk_key, body, query=None, extra_headers=None):  #
             headers.update(extra_headers)
 
         try:
-            response = requests.post(
+            session = requests.Session()
+            session = self._request_decorator.decorate_headers(session)
+            response = session.post(
                 self._build_url(server, path),
                 json=body,
                 params=query,
@@ -147,3 +156,5 @@ def post(self, server, path, sdk_key, body, query=None, extra_headers=None):  #
             return HttpResponse(response.status_code, response.text)
         except Exception as exc:  # pylint: disable=broad-except
             raise HttpClientException('requests library is throwing exceptions') from exc
+        finally:
+            session.close()
diff --git a/tests/api/test_httpclient.py b/tests/api/test_httpclient.py
index 694c9a22..74725cf3 100644
--- a/tests/api/test_httpclient.py
+++ b/tests/api/test_httpclient.py
@@ -1,6 +1,8 @@
 """HTTPClient test module."""
+import pytest
 
 from splitio.api import client
+from splitio.api.request_decorator import RequestDecorator, NoOpHeaderDecorator, UserCustomHeaderDecorator
 
 class HttpClientTests(object):
     """Http Client test cases."""
@@ -12,8 +14,9 @@ def test_get(self, mocker):
         response_mock.text = 'ok'
         get_mock = mocker.Mock()
         get_mock.return_value = response_mock
-        mocker.patch('splitio.api.client.requests.get', new=get_mock)
-        httpclient = client.HttpClient()
+        mocker.patch('splitio.api.client.requests.Session.get', new=get_mock)
+
+        httpclient = client.HttpClient(RequestDecorator(NoOpHeaderDecorator()))
         response = httpclient.get('sdk', '/test1', 'some_api_key', {'param1': 123}, {'h1': 'abc'})
         call = mocker.call(
             client.HttpClient.SDK_URL + '/test1',
@@ -44,8 +47,8 @@ def test_get_custom_urls(self, mocker):
         response_mock.text = 'ok'
         get_mock = mocker.Mock()
         get_mock.return_value = response_mock
-        mocker.patch('splitio.api.client.requests.get', new=get_mock)
-        httpclient = client.HttpClient(sdk_url='https://sdk.com', events_url='https://events.com')
+        mocker.patch('splitio.api.client.requests.Session.get', new=get_mock)
+        httpclient = client.HttpClient(RequestDecorator(NoOpHeaderDecorator()), sdk_url='https://sdk.com', events_url='https://events.com')
         response = httpclient.get('sdk', '/test1', 'some_api_key', {'param1': 123}, {'h1': 'abc'})
         call = mocker.call(
             'https://sdk.com/test1',
@@ -69,6 +72,40 @@ def test_get_custom_urls(self, mocker):
         assert response.body == 'ok'
         assert get_mock.mock_calls == [call]
 
+    def test_get_custom_headers(self, mocker):
+        """Test HTTP GET verb requests."""
+        response_mock = mocker.Mock()
+        response_mock.status_code = 200
+        response_mock.text = 'ok'
+        get_mock = mocker.Mock()
+        get_mock.return_value = response_mock
+        mocker.patch('splitio.api.client.requests.Session.get', new=get_mock)
+
+        class MyCustomDecorator(UserCustomHeaderDecorator):
+            def get_header_overrides(self):
+                return {"UserCustomHeader": "value", "AnotherCustomHeader": "val"}
+
+        global current_session
+        current_session = None
+        class RequestDecoratorWrapper(RequestDecorator):
+            def decorate_headers(self, session):
+                global current_session
+                current_session = session
+                return RequestDecorator.decorate_headers(self, session)
+
+        httpclient = client.HttpClient(RequestDecoratorWrapper(MyCustomDecorator()))
+        response = httpclient.get('sdk', '/test1', 'some_api_key', {'param1': 123}, {'h1': 'abc'})
+        call = mocker.call(
+            client.HttpClient.SDK_URL + '/test1',
+            headers={'Authorization': 'Bearer some_api_key', 'h1': 'abc', 'Content-Type': 'application/json'},
+            params={'param1': 123},
+            timeout=None
+        )
+        assert current_session.headers["UserCustomHeader"] == "value"
+        assert current_session.headers["AnotherCustomHeader"] == "val"
+        assert response.status_code == 200
+        assert response.body == 'ok'
+        assert get_mock.mock_calls == [call]
 
     def test_post(self, mocker):
         """Test HTTP GET verb requests."""
@@ -77,8 +114,8 @@ def test_post(self, mocker):
         response_mock.text = 'ok'
         get_mock = mocker.Mock()
         get_mock.return_value = response_mock
-        mocker.patch('splitio.api.client.requests.post', new=get_mock)
-        httpclient = client.HttpClient()
+        mocker.patch('splitio.api.client.requests.Session.post', new=get_mock)
+        httpclient = client.HttpClient(RequestDecorator(NoOpHeaderDecorator()))
         response = httpclient.post('sdk', '/test1', 'some_api_key', {'p1': 'a'}, {'param1': 123}, {'h1': 'abc'})
         call = mocker.call(
             client.HttpClient.SDK_URL + '/test1',
@@ -111,8 +148,8 @@ def test_post_custom_urls(self, mocker):
         response_mock.text = 'ok'
         get_mock = mocker.Mock()
         get_mock.return_value = response_mock
-        mocker.patch('splitio.api.client.requests.post', new=get_mock)
-        httpclient = client.HttpClient(sdk_url='https://sdk.com', events_url='https://events.com')
+        mocker.patch('splitio.api.client.requests.Session.post', new=get_mock)
+        httpclient = client.HttpClient(RequestDecorator(NoOpHeaderDecorator()), sdk_url='https://sdk.com', events_url='https://events.com')
         response = httpclient.post('sdk', '/test1', 'some_api_key', {'p1': 'a'}, {'param1': 123}, {'h1': 'abc'})
         call = mocker.call(
             'https://sdk.com' + '/test1',
@@ -137,3 +174,38 @@ def test_post_custom_urls(self, mocker):
         assert response.status_code == 200
         assert response.body == 'ok'
         assert get_mock.mock_calls == [call]
+
+    def test_post_custom_headers(self, mocker):
+        """Test HTTP GET verb requests."""
+        response_mock = mocker.Mock()
+        response_mock.status_code = 200
+        response_mock.text = 'ok'
+        get_mock = mocker.Mock()
+        get_mock.return_value = response_mock
+        mocker.patch('splitio.api.client.requests.Session.post', new=get_mock)
+        class MyCustomDecorator(UserCustomHeaderDecorator):
+            def get_header_overrides(self):
+                return {"UserCustomHeader": "value", "AnotherCustomHeader": "val"}
+
+        global current_session
+        current_session = None
+        class RequestDecoratorWrapper(RequestDecorator):
+            def decorate_headers(self, session):
+                global current_session
+                current_session = session
+                return RequestDecorator.decorate_headers(self, session)
+
+        httpclient = client.HttpClient(RequestDecoratorWrapper(MyCustomDecorator()))
+        response = httpclient.post('sdk', '/test1', 'some_api_key', {'p1': 'a'}, {'param1': 123}, {'h1': 'abc'})
+        call = mocker.call(
+            client.HttpClient.SDK_URL + '/test1',
+            json={'p1': 'a'},
+            headers={'Authorization': 'Bearer some_api_key', 'h1': 'abc', 'Content-Type': 'application/json'},
+            params={'param1': 123},
+            timeout=None
+        )
+        assert current_session.headers["UserCustomHeader"] == "value"
+        assert current_session.headers["AnotherCustomHeader"] == "val"
+        assert response.status_code == 200
+        assert response.body == 'ok'
+        assert get_mock.mock_calls == [call]
\ No newline at end of file