diff --git a/lib/fulfil/query.rb b/lib/fulfil/query.rb
index 2218e91..54435a9 100644
--- a/lib/fulfil/query.rb
+++ b/lib/fulfil/query.rb
@@ -1,5 +1,8 @@
 # frozen_string_literal: true
 
+require 'date'
+require 'fulfil/converter'
+
 module Fulfil
   class Query
     def initialize
@@ -86,11 +89,25 @@ def build_search_term(field:, value:, options:, prefix: nil)
           [[key, 'ilike', value]]
         end
       when 'Hash'
+        handle_hash(field, key, value, options)
+      when 'Date', 'DateTime'
+        [[key, '=', Converter.date_or_datetime_as_object(value)]]
+      else
+        raise "Unhandled value type: #{value} (#{value.class.name})"
+      end
+    end
+
+    def handle_hash(field, key, value, options)
+      if %i[gte gt lte lt].any? { |op| value.key?(op) }
+        value.map do |operator, val|
+          op_map = { gte: '>=', gt: '>', lte: '<=', lt: '<' }
+          converted_value = Converter.date_or_datetime_as_object(val)
+          [key, op_map[operator], converted_value]
+        end
+      else
         value.flat_map do |nested_field, nested_value|
           build_search_term(prefix: field, field: nested_field, value: nested_value, options: options)
         end
-      else
-        raise "Unhandled value type: #{value} (#{value.class.name})"
       end
     end
 
diff --git a/test/fulfil/query_test.rb b/test/fulfil/query_test.rb
index de7bc28..231e58e 100644
--- a/test/fulfil/query_test.rb
+++ b/test/fulfil/query_test.rb
@@ -2,7 +2,10 @@
 
 require 'minitest/autorun'
 require 'fulfil/query'
+require 'fulfil/converter'
+require 'date'
 
+# rubocop:disable Metrics/ClassLength
 module Fulfil
   class QueryTest < Minitest::Test
     def setup
@@ -47,6 +50,32 @@ def test_nested_queries
       assert_equal [['sale.id', 'in', [123]]], @query.query
     end
 
+    def test_dates_are_converted_to_iso8601
+      date = Date.new(2019, 1, 1)
+      expected_date_format = Converter.date_as_object(date)
+
+      @query.search(date: date)
+
+      assert_equal [['date', '=', expected_date_format]], @query.query
+    end
+
+    def test_date_greater_than_or_equal_to_converted_to_iso8601
+      date = Date.new(2019, 1, 1)
+      expected_date_format = Converter.date_as_object(date)
+
+      @query.search(date: { gte: date })
+
+      assert_equal [['date', '>=', expected_date_format]], @query.query
+    end
+
+    def test_datetime_less_than_converted_to_iso8601
+      datetime = DateTime.new(2019, 1, 1, 0, 0, 0)
+      expected_datetime_format = Converter.datetime_as_object(datetime)
+
+      @query.search(datetime: { lt: datetime })
+
+      assert_equal [['datetime', '<', expected_datetime_format]], @query.query
+    end
     # -- #exclude -----------------------
 
     def test_equals_exclude
@@ -183,3 +212,4 @@ def test_chaining
     end
   end
 end
+# rubocop:enable Metrics/ClassLength