diff --git a/qiskit/providers/ibmq/api/rest/job.py b/qiskit/providers/ibmq/api/rest/job.py
index bb2d7fef9..ecea7c184 100644
--- a/qiskit/providers/ibmq/api/rest/job.py
+++ b/qiskit/providers/ibmq/api/rest/job.py
@@ -15,11 +15,14 @@
 """Job REST adapter for the IBM Q Experience API."""
 
 import pprint
+import json
 from json.decoder import JSONDecodeError
 
 from typing import Dict, Any
 from marshmallow.exceptions import ValidationError
 
+from qiskit.providers.ibmq.utils import json_encoder
+
 from .base import RestAdapterBase
 from .validation import StatusResponseSchema
 from ..session import RetrySession
@@ -137,7 +140,8 @@ def put_object_storage(self, url: str, qobj_dict: Dict[str, Any]) -> str:
         Returns:
             text response, that will be empty if the request was successful.
         """
-        response = self.session.put(url, json=qobj_dict, bare=True)
+        data = json.dumps(qobj_dict, cls=json_encoder.IQXJsonEconder)
+        response = self.session.put(url, data=data, bare=True)
         return response.text
 
     def get_object_storage(self, url: str) -> Dict[str, Any]:
diff --git a/qiskit/providers/ibmq/api/rest/root.py b/qiskit/providers/ibmq/api/rest/root.py
index e3e352ba2..760d9c359 100644
--- a/qiskit/providers/ibmq/api/rest/root.py
+++ b/qiskit/providers/ibmq/api/rest/root.py
@@ -18,6 +18,8 @@
 
 from typing import Dict, List, Optional, Any
 
+from qiskit.providers.ibmq.utils import json_encoder
+
 from .base import RestAdapterBase
 from .backend import Backend
 from .job import Job
@@ -140,7 +142,8 @@ def job_submit(
         if job_tags:
             payload['tags'] = job_tags
 
-        return self.session.post(url, json=payload).json()
+        data = json.dumps(payload, cls=json_encoder.IQXJsonEconder)
+        return self.session.post(url, data=data).json()
 
     def submit_job_object_storage(
             self,
diff --git a/qiskit/providers/ibmq/utils/json_encoder.py b/qiskit/providers/ibmq/utils/json_encoder.py
new file mode 100644
index 000000000..4d3f543bb
--- /dev/null
+++ b/qiskit/providers/ibmq/utils/json_encoder.py
@@ -0,0 +1,33 @@
+# -*- coding: utf-8 -*-
+
+# This code is part of Qiskit.
+#
+# (C) Copyright IBM 2020.
+#
+# This code is licensed under the Apache License, Version 2.0. You may
+# obtain a copy of this license in the LICENSE.txt file in the root directory
+# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
+#
+# Any modifications or derivative works of this code must retain this
+# copyright notice, and modified files need to carry a notice indicating
+# that they have been altered from the originals.
+
+# pylint: disable=method-hidden
+
+"""Custom JSON encoders."""
+
+import json
+from typing import Any
+
+
+class IQXJsonEconder(json.JSONEncoder):
+    """A json encoder for qobj"""
+
+    def default(self, o: Any) -> Any:
+        # Convert numpy arrays:
+        if hasattr(o, 'tolist'):
+            return o.tolist()
+        # Use Qobj complex json format:
+        if isinstance(o, complex):
+            return (o.real, o.imag)
+        return json.JSONEncoder.default(self, o)