diff --git a/doc/topics/install.rst b/doc/topics/install.rst
index ba7c59a8fe..a449ead743 100644
--- a/doc/topics/install.rst
+++ b/doc/topics/install.rst
@@ -23,7 +23,6 @@ Prerequisites
     * Optional: pydot (http://code.google.com/p/pydot/)
     * Optional: unoconv http://dag.wieers.com/home-made/unoconv/)
     * Optional: sphinx (http://sphinx.pocoo.org/)
-    * Optional: simplejson (http://undefined.org/python/#simplejson)
     * Optional: cdecimal (http://www.bytereef.org/mpdecimal/index.html)
     * Optional: python-Levenshtein
       (http://github.com/miohtama/python-Levenshtein)
diff --git a/setup.py b/setup.py
index c512efdec8..65c09fd1e7 100644
--- a/setup.py
+++ b/setup.py
@@ -106,7 +106,6 @@ setup(name=name,
         'MySQL': ['MySQL-python'],
         'unoconv': ['unoconv'],
         'graphviz': ['pydot'],
-        'simplejson': ['simplejson'],
         'cdecimal': ['cdecimal'],
         'Levenshtein': ['python-Levenshtein'],
         'BCrypt': ['bcrypt'],
diff --git a/trytond/ir/model.py b/trytond/ir/model.py
index 138ef24b74..f0498bfae3 100644
--- a/trytond/ir/model.py
+++ b/trytond/ir/model.py
@@ -2,16 +2,13 @@
 # this repository contains the full copyright notices and license terms.
 import re
 import heapq
+import json
 
 from sql import Null
 from sql.aggregate import Max
 from sql.conditionals import Case
 from collections import defaultdict
 from itertools import groupby
-try:
-    import simplejson as json
-except ImportError:
-    import json
 
 from ..model import (ModelView, ModelSQL, Workflow, fields, Unique,
     EvalEnvironment)
diff --git a/trytond/ir/session.py b/trytond/ir/session.py
index c1c8c789dd..80cd99ab09 100644
--- a/trytond/ir/session.py
+++ b/trytond/ir/session.py
@@ -1,9 +1,6 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
-try:
-    import simplejson as json
-except ImportError:
-    import json
+import json
 import uuid
 import datetime
 
diff --git a/trytond/ir/ui/view.py b/trytond/ir/ui/view.py
index 33a4b7070b..395bca5ce3 100644
--- a/trytond/ir/ui/view.py
+++ b/trytond/ir/ui/view.py
@@ -3,10 +3,7 @@
 import os
 import sys
 import logging
-try:
-    import simplejson as json
-except ImportError:
-    import json
+import json
 
 from lxml import etree
 from trytond.model import ModelView, ModelSQL, fields
diff --git a/trytond/model/dictschema.py b/trytond/model/dictschema.py
index 34363a8d5f..38ed0f5feb 100644
--- a/trytond/model/dictschema.py
+++ b/trytond/model/dictschema.py
@@ -1,10 +1,7 @@
 # This file is part of Tryton.  The COPYRIGHT file at the toplevel of this
 # repository contains the full copyright notices and license terms.
+import json
 from collections import OrderedDict
-try:
-    import simplejson as json
-except ImportError:
-    import json
 
 from trytond.model import fields
 from trytond.pyson import Eval
diff --git a/trytond/model/fields/dict.py b/trytond/model/fields/dict.py
index be65ba2ec2..1f218078eb 100644
--- a/trytond/model/fields/dict.py
+++ b/trytond/model/fields/dict.py
@@ -1,9 +1,6 @@
 # This file is part of Tryton.  The COPYRIGHT file at the toplevel of this
 # repository contains the full copyright notices and license terms.
-try:
-    import simplejson as json
-except ImportError:
-    import json
+import json
 from sql import Query, Expression
 
 from .field import Field, SQLType
diff --git a/trytond/protocols/jsonrpc.py b/trytond/protocols/jsonrpc.py
index b91fa2cd49..659814290f 100644
--- a/trytond/protocols/jsonrpc.py
+++ b/trytond/protocols/jsonrpc.py
@@ -2,10 +2,7 @@
 # this repository contains the full copyright notices and license terms.
 import datetime
 from decimal import Decimal
-try:
-    import simplejson as json
-except ImportError:
-    import json
+import json
 import base64
 
 from werkzeug.wrappers import Response
@@ -53,11 +50,6 @@ class JSONEncoder(json.JSONEncoder):
 
     serializers = {}
 
-    def __init__(self, *args, **kwargs):
-        super(JSONEncoder, self).__init__(*args, **kwargs)
-        # Force to use our custom decimal with simplejson
-        self.use_decimal = False
-
     @classmethod
     def register(cls, klass, encoder):
         assert klass not in cls.serializers
diff --git a/trytond/pyson.py b/trytond/pyson.py
index 23137c06ca..6620c84420 100644
--- a/trytond/pyson.py
+++ b/trytond/pyson.py
@@ -1,9 +1,6 @@
 # This file is part of Tryton.  The COPYRIGHT file at the top level of
 # this repository contains the full copyright notices and license terms.
-try:
-    import simplejson as json
-except ImportError:
-    import json
+import json
 import datetime
 from dateutil.relativedelta import relativedelta
 from functools import reduce, wraps
diff --git a/trytond/wizard/wizard.py b/trytond/wizard/wizard.py
index fc8f430e2a..f1d2abed1c 100644
--- a/trytond/wizard/wizard.py
+++ b/trytond/wizard/wizard.py
@@ -5,10 +5,7 @@ __all__ = ['Wizard',
     'StateView', 'StateTransition', 'StateAction', 'StateReport',
     'Button']
 
-try:
-    import simplejson as json
-except ImportError:
-    import json
+import json
 import copy
 
 from trytond.pool import Pool, PoolBase