diff --git a/.drone.yml b/.drone.yml
index a4d2595986..70b0581c7c 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -1,9 +1,9 @@
-image: python2.7
+image: python:all
 env:
   - POSTGRESQL_URI=postgresql://postgres@127.0.0.1:5432/
   - MYSQL_URI=mysql://root@127.0.0.1:3306/
 script:
   - pip install tox
-  - tox -e sqlite,postgresql
+  - tox -e "{py27,py33,py34,py35}-{sqlite,postgresql}"
 services:
   - postgres
diff --git a/CHANGELOG b/CHANGELOG
index b808476d5c..e94e4387d4 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,4 @@
+* Add Python3 support
 * Switch to ldap3
 
 Version 4.0.0 - 2016-05-02
diff --git a/res.py b/res.py
index e0c88d8000..a073faff30 100644
--- a/res.py
+++ b/res.py
@@ -10,14 +10,13 @@ from trytond.config import config, parse_uri
 from trytond.exceptions import LoginException
 
 __all__ = ['User']
-__metaclass__ = PoolMeta
 
 logger = logging.getLogger(__name__)
 section = 'ldap_authentication'
 
 # Old version of urlparse doesn't parse query for ldap
 # see http://bugs.python.org/issue9374
-if hasattr(urlparse, 'uses_query') and 'ldap' not in urlparse.uses_query:
+if 'ldap' not in urlparse.uses_query:
     urlparse.uses_query.append('ldap')
 
 
@@ -48,6 +47,7 @@ def ldap_server():
 
 
 class User:
+    __metaclass__ = PoolMeta
     __name__ = 'res.user'
 
     @classmethod
diff --git a/setup.py b/setup.py
index 60e1901a85..c6fd12c06c 100644
--- a/setup.py
+++ b/setup.py
@@ -5,11 +5,17 @@
 from setuptools import setup
 import re
 import os
-import ConfigParser
+import io
+try:
+    from configparser import ConfigParser
+except ImportError:
+    from ConfigParser import ConfigParser
 
 
 def read(fname):
-    return open(os.path.join(os.path.dirname(__file__), fname)).read()
+    return io.open(
+        os.path.join(os.path.dirname(__file__), fname),
+        'r', encoding='utf-8').read()
 
 
 def get_require_version(name):
@@ -21,7 +27,7 @@ def get_require_version(name):
         major_version, minor_version + 1)
     return require
 
-config = ConfigParser.ConfigParser()
+config = ConfigParser()
 config.readfp(open('tryton.cfg'))
 info = dict(config.items('tryton'))
 for key in ('depends', 'extras_depend', 'xml'):
@@ -91,6 +97,11 @@ setup(name=name,
         'Natural Language :: Spanish',
         'Operating System :: OS Independent',
         'Programming Language :: Python :: 2.7',
+        'Programming Language :: Python :: 3.3',
+        'Programming Language :: Python :: 3.4',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: Implementation :: CPython',
+        'Programming Language :: Python :: Implementation :: PyPy',
         'Topic :: Office/Business',
         ('Topic :: System :: Systems Administration '
             ':: Authentication/Directory :: LDAP'),
@@ -105,4 +116,5 @@ setup(name=name,
     test_suite='tests',
     test_loader='trytond.test_loader:Loader',
     tests_require=tests_require,
+    use_2to3=True,
     )
diff --git a/tox.ini b/tox.ini
index dcaeecdee9..8bba82c5c8 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,10 +1,10 @@
 [tox]
-envlist = py27-{sqlite,postgresql,mysql}
+envlist = {py27,py33,py34,py35}-{sqlite,postgresql,mysql},pypy-{sqlite,postgresql}
 
 [testenv]
 commands = {envpython} setup.py test
 deps =
-    postgresql: psycopg2 >= 2.5
+    {py27,py33,py34,py35}-postgresql: psycopg2 >= 2.5
     mysql: MySQL-python
 setenv =
     sqlite: TRYTOND_DATABASE_URI={env:SQLITE_URI:sqlite://}