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 ef76b2a74f..06c6095bee 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 b6abe9f7b6..1d935d8be3 100644
--- a/account.py
+++ b/account.py
@@ -6,10 +6,10 @@ from trytond.pool import PoolMeta
 
 
 __all__ = ['Move']
-__metaclass__ = PoolMeta
 
 
 class Move:
+    __metaclass__ = PoolMeta
     __name__ = 'account.move'
 
     @classmethod
diff --git a/commission.py b/commission.py
index 58f15ca766..150862629d 100644
--- a/commission.py
+++ b/commission.py
@@ -8,10 +8,10 @@ from trytond.pyson import Eval, Bool
 
 
 __all__ = ['Agent', 'Commission']
-__metaclass__ = PoolMeta
 
 
 class Agent:
+    __metaclass__ = PoolMeta
     __name__ = 'commission.agent'
     waiting_account = fields.Many2One('account.account', 'Waiting Account',
         domain=[
@@ -22,6 +22,7 @@ class Agent:
 
 
 class Commission:
+    __metaclass__ = PoolMeta
     __name__ = 'commission'
     waiting_move = fields.Many2One('account.move', 'Move', readonly=True)
 
diff --git a/invoice.py b/invoice.py
index 7ed13cd0f2..b656a7bbba 100644
--- a/invoice.py
+++ b/invoice.py
@@ -8,10 +8,10 @@ from trytond.model import ModelView, Workflow
 
 
 __all__ = ['Invoice', 'InvoiceLine']
-__metaclass__ = PoolMeta
 
 
 class Invoice:
+    __metaclass__ = PoolMeta
     __name__ = 'account.invoice'
 
     @classmethod
@@ -48,6 +48,7 @@ class Invoice:
 
 
 class InvoiceLine:
+    __metaclass__ = PoolMeta
     __name__ = 'account.invoice.line'
 
     def get_move_line(self):
diff --git a/setup.py b/setup.py
index 7aa9c730e2..2c32bbbaca 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'):
@@ -94,6 +100,9 @@ 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',
@@ -110,4 +119,8 @@ setup(name=name,
     test_suite='tests',
     test_loader='trytond.test_loader:Loader',
     tests_require=tests_require,
+    use_2to3=True,
+    convert_2to3_doctests=[
+        'tests/scenario_commission_waiting.rst',
+        ],
     )
diff --git a/tests/scenario_commission_waiting.rst b/tests/scenario_commission_waiting.rst
index dd1d50d393..e5c6a1edcd 100644
--- a/tests/scenario_commission_waiting.rst
+++ b/tests/scenario_commission_waiting.rst
@@ -12,7 +12,7 @@ Imports::
     ...     get_company
     >>> from trytond.modules.account.tests.tools import create_fiscalyear, \
     ...     create_chart, get_accounts, create_tax, set_tax_code
-    >>> from.trytond.modules.account_invoice.tests.tools import \
+    >>> from trytond.modules.account_invoice.tests.tools import \
     ...     set_fiscalyear_invoice_sequences, create_payment_term
     >>> today = datetime.date.today()
 
diff --git a/tests/test_commission_waiting.py b/tests/test_commission_waiting.py
index 74a85aedc9..c3eb328c87 100644
--- a/tests/test_commission_waiting.py
+++ b/tests/test_commission_waiting.py
@@ -8,6 +8,7 @@ import doctest
 from trytond.tests.test_tryton import ModuleTestCase
 from trytond.tests.test_tryton import suite as test_suite
 from trytond.tests.test_tryton import doctest_setup, doctest_teardown
+from trytond.tests.test_tryton import doctest_checker
 
 
 class CommissionWaitingTestCase(ModuleTestCase):
@@ -21,5 +22,6 @@ def suite():
             CommissionWaitingTestCase))
     suite.addTests(doctest.DocFileSuite('scenario_commission_waiting.rst',
             setUp=doctest_setup, tearDown=doctest_teardown, encoding='utf-8',
+            checker=doctest_checker,
             optionflags=doctest.REPORT_ONLY_FIRST_FAILURE))
     return 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 =