diff --git a/msrest/serialization.py b/msrest/serialization.py
index f9037b9..378de20 100644
--- a/msrest/serialization.py
+++ b/msrest/serialization.py
@@ -953,6 +953,16 @@ class Serializer(object):
             return self.serialize_long(attr)
         if obj_type is unicode_str:
             return self.serialize_unicode(attr)
+        if obj_type is datetime.datetime:
+            return self.serialize_iso(attr)
+        if obj_type is datetime.date:
+            return self.serialize_date(attr)
+        if obj_type is datetime.time:
+            return self.serialize_time(attr)
+        if obj_type is datetime.timedelta:
+            return self.serialize_duration(attr)
+        if obj_type is decimal.Decimal:
+            return self.serialize_decimal(attr)
 
         # If it's a model or I know this dependency, serialize as a Model
         elif obj_type in self.dependencies.values() or isinstance(attr, Model):
diff --git a/tests/test_serialization.py b/tests/test_serialization.py
index ab04cfd..6837bad 100644
--- a/tests/test_serialization.py
+++ b/tests/test_serialization.py
@@ -25,6 +25,7 @@
 #
 #--------------------------------------------------------------------------
 
+from decimal import Decimal
 import sys
 import json
 import isodate
@@ -1395,6 +1396,42 @@ class TestRuntimeSerialized(unittest.TestCase):
             'data': {'id': u"\ua015"}
         }
 
+    def test_datetime_types_as_type_object(self):
+        """https://github.com/Azure/msrest-for-python/issues/223
+        """
+
+        class TestModel(Model):
+            _attribute_map = {'data': {'key': 'data', 'type': 'object'}}
+
+        m = TestModel(data = {
+            'datetime': isodate.parse_datetime('2012-02-24T00:53:52.780Z'),
+            'date': date(2019,5,1),
+            'time': time(11,12,13),
+            'timedelta': timedelta(56)
+        })
+        serialized = m.serialize()
+        assert serialized['data'] == {
+            'datetime': '2012-02-24T00:53:52.780Z',
+            'date': '2019-05-01',
+            'time': '11:12:13',
+            'timedelta': 'P56D'
+        }
+
+    def test_decimal_types_as_type_object(self):
+        """https://github.com/Azure/msrest-for-python/issues/223
+        """
+
+        class TestModel(Model):
+            _attribute_map = {'data': {'key': 'data', 'type': 'object'}}
+
+        m = TestModel(data = {
+            'decimal': Decimal('1.1'),
+        })
+        serialized = m.serialize()
+        assert serialized['data'] == {
+            'decimal': 1.1
+        }
+
     def test_json_with_xml_map(self):
         basic_json = {'age': 37, 'country': 'france'}