diff --git a/.drone.yml b/.drone.yml
index 9d7c769d8c..c4fd423e94 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 "py27-{sqlite,postgresql}"
+  - tox -e "{py27,py33,py34,py35}-{sqlite,postgresql}" --skip-missing-interpreters
 services:
   - postgres
diff --git a/CHANGELOG b/CHANGELOG
index 8d80dcb621..66333ba609 100644
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,5 @@
+* Add Python3 support
+
 Version 3.8.0 - 2015-11-02
 * Bug fixes (see mercurial logs for details)
 
diff --git a/account.py b/account.py
index 952ee74a7e..631a2f8656 100644
--- a/account.py
+++ b/account.py
@@ -8,10 +8,10 @@ from trytond.transaction import Transaction
 from trytond.pyson import Eval
 
 __all__ = ['Configuration', 'Level']
-__metaclass__ = PoolMeta
 
 
 class Configuration:
+    __metaclass__ = PoolMeta
     __name__ = 'account.configuration'
 
     default_credit_limit_amount = fields.Function(fields.Numeric(
@@ -76,6 +76,7 @@ class Configuration:
 
 
 class Level:
+    __metaclass__ = PoolMeta
     __name__ = 'account.dunning.level'
     credit_limit = fields.Boolean('Credit Limit',
         help='Has reached the credit limit')
diff --git a/party.py b/party.py
index b11e2272e6..ae1f84c743 100644
--- a/party.py
+++ b/party.py
@@ -6,10 +6,10 @@ from trytond.transaction import Transaction
 from trytond.pyson import Eval
 
 __all__ = ['Party']
-__metaclass__ = PoolMeta
 
 
 class Party:
+    __metaclass__ = PoolMeta
     __name__ = 'party.party'
 
     credit_amount = fields.Function(fields.Numeric('Credit Amount',
diff --git a/setup.py b/setup.py
index fe91e15a11..06b3931704 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'):
@@ -88,6 +94,9 @@ 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',
@@ -102,4 +111,5 @@ setup(name=name,
     """,
     test_suite='tests',
     test_loader='trytond.test_loader:Loader',
+    use_2to3=True,
     )
diff --git a/tests/__init__.py b/tests/__init__.py
index 6ec40fdb45..24c12e2be7 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -1,6 +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.
 
-from test_account_credit_limit import suite
+from .test_account_credit_limit import suite
 
 __all__ = ['suite']
diff --git a/tox.ini b/tox.ini
index e9d2876444..e2a064851d 100644
--- a/tox.ini
+++ b/tox.ini
@@ -1,10 +1,10 @@
 [tox]
-envlist = py27-{sqlite,postgresql,mysql},pypy-{sqlite,postgresql}
+envlist = {py27,py33,py34,py35}-{sqlite,postgresql,mysql},pypy-{sqlite,postgresql}
 
 [testenv]
 commands = {envpython} setup.py test
 deps =
-    py27-postgresql: psycopg2 >= 2.0
+    {py27,py33,py34,py35}-postgresql: psycopg2 >= 2.0
     pypy-postgresql: psycopg2cffi >= 2.5
     mysql: MySQL-python
 setenv =