diff -r a0c687dc0039 Lib/pprint.py
--- a/Lib/pprint.py	Tue Dec 10 13:53:56 2013 +0200
+++ b/Lib/pprint.py	Tue Dec 10 21:15:52 2013 +0200
@@ -37,7 +37,8 @@
 import re
 import sys as _sys
 from collections import OrderedDict as _OrderedDict
-from io import StringIO as _StringIO
+from io import StringIO as _StringIO, TextIOWrapper as _TextIOWrapper, \
+               RawIOBase as _RawIOBase
 
 __all__ = ["pprint","pformat","isreadable","isrecursive","saferepr",
            "PrettyPrinter"]
@@ -129,10 +130,28 @@
         self._depth = depth
         self._indent_per_level = indent
         self._width = width
-        if stream is not None:
-            self._stream = stream
-        else:
-            self._stream = _sys.stdout
+        if stream is None:
+            stream = _sys.stdout
+        encoding = getattr(stream, 'encoding', None)
+        if encoding:
+            oldstream = stream
+            buffer = getattr(stream, 'buffer', None)
+            if buffer is None:
+                class DecodeWriter(_RawIOBase):
+                    def writable(self):
+                        return True
+                    def write(self, data):
+                        return oldstream.write(data.decode(encoding))
+                buffer = DecodeWriter()
+            stream.flush()
+            stream = _TextIOWrapper(buffer, encoding=encoding,
+                                    errors='backslashreplace',
+                                    newline='\n', write_through=True)
+            def close():
+                oldstream.flush()
+                stream.detach()
+            stream.close = close
+        self._stream = stream
         self._compact = bool(compact)
 
     def pprint(self, object):
diff -r a0c687dc0039 Lib/test/test_pprint.py
--- a/Lib/test/test_pprint.py	Tue Dec 10 13:53:56 2013 +0200
+++ b/Lib/test/test_pprint.py	Tue Dec 10 21:15:52 2013 +0200
@@ -7,6 +7,7 @@
 import random
 import collections
 import itertools
+import io
 
 # list, tuple and dict subclasses that do or don't overwrite __repr__
 class list2(list):
@@ -580,6 +581,38 @@
  [0, 1, 2, 3, 4]]"""
         self.assertEqual(pprint.pformat(o, width=48, compact=True), expected)
 
+    def test_unencodable(self):
+        # with encoding and buffer
+        with io.BytesIO() as bio, \
+             io.TextIOWrapper(bio, encoding='latin1') as stream:
+            stream.write('\xab')
+            pprint.pprint('\xa3\u20ac', stream)
+            self.assertFalse(bio.closed)
+            self.assertEqual(bio.getvalue(), b"\xab'\xa3\\u20ac'\n")
+            stream.write('\xbb')
+            stream.flush()
+            self.assertFalse(bio.closed)
+            self.assertEqual(bio.getvalue(), b"\xab'\xa3\\u20ac'\n\xbb")
+        # without encoding and buffer
+        with io.StringIO() as stream:
+            stream.write('\xab')
+            pprint.pprint('\xa3\u20ac', stream)
+            self.assertEqual(stream.getvalue(), "\xab'\xa3\u20ac'\n")
+            stream.write('\xbb')
+            self.assertEqual(stream.getvalue(), "\xab'\xa3\u20ac'\n\xbb")
+        # with encoding but without buffer
+        class MockWriter(list):
+            encoding = 'latin1'
+            write = list.append
+            def flush(self):
+                pass
+        stream = MockWriter()
+        stream.write('\xab')
+        pprint.pprint('\xa3\u20ac', stream)
+        self.assertEqual(''.join(stream), "\xab'\xa3\\u20ac'\n")
+        stream.write('\xbb')
+        self.assertEqual(''.join(stream), "\xab'\xa3\\u20ac'\n\xbb")
+
 
 class DottedPrettyPrinter(pprint.PrettyPrinter):