diff -r d37e44c917f5 Lib/gzip.py
--- a/Lib/gzip.py	Thu Jul 14 12:48:25 2011 -0500
+++ b/Lib/gzip.py	Thu Jul 14 21:18:03 2011 +0200
@@ -24,14 +24,21 @@
 def read32(input):
     return struct.unpack("<I", input.read(4))[0]
 
-def open(filename, mode="rb", compresslevel=9):
+def open(filename, mode="rb", compresslevel=9, *, encoding=None):
     """Shorthand for GzipFile(filename, mode, compresslevel).
 
     The filename argument is required; mode defaults to 'rb'
     and compresslevel defaults to 9.
 
+    If the optional encoding argument is given, the GzipFile
+    object will be wrapped in a TextIOWrapper with the specified
+    encoding.
+
     """
-    return GzipFile(filename, mode, compresslevel)
+    gf = GzipFile(filename, mode, compresslevel)
+    if encoding is not None:
+        gf = io.TextIOWrapper(gf, encoding=encoding)
+    return gf
 
 class _PaddedFile:
     """Minimal read-only file object that prepends a string to the contents
diff -r d37e44c917f5 Lib/test/test_gzip.py
--- a/Lib/test/test_gzip.py	Thu Jul 14 12:48:25 2011 -0500
+++ b/Lib/test/test_gzip.py	Thu Jul 14 21:18:03 2011 +0200
@@ -21,6 +21,8 @@
 /* See http://www.winimage.com/zLibDll for Windows */
 """
 
+textdata = '\u00c1rv\u00edzt\u0171r\u0151 T\u00fck\u00f6rf\u00far\u00f3g\u00e9p'
+
 
 class UnseekableIO(io.BytesIO):
     def seekable(self):
@@ -366,6 +368,18 @@
             datac = gzip.compress(data)
             self.assertEqual(gzip.decompress(datac), data)
 
+    def test_encoding(self):
+        # test the encoding argument of gzip.open (issue12559)
+        for enc in ('UTF-8', 'UTF-16', 'UTF-32', 'latin2'):
+            with gzip.open(self.filename, 'w') as f:
+                data = (textdata * 100).encode(enc)
+                f.write(data)
+            with gzip.open(self.filename, 'r', encoding=enc) as f:
+                self.assertEqual(f.read(), textdata * 100)
+            with gzip.open(self.filename, 'r') as f:
+                self.assertEqual(f.read(), data)
+
+
 def test_main(verbose=None):
     support.run_unittest(TestGzip)