diff --git a/pandas/core/tools/datetimes.py b/pandas/core/tools/datetimes.py
index cbe27efb043bf8..62f38e288a4d91 100644
--- a/pandas/core/tools/datetimes.py
+++ b/pandas/core/tools/datetimes.py
@@ -31,6 +31,7 @@
 from pandas.core import algorithms
 from pandas.compat import PY3, zip
 
+
 def _guess_datetime_format_for_array(arr, **kwargs):
     # Try to guess the format based on the first non-NaN element
     non_nan_elements = notna(arr).nonzero()[0]
@@ -362,11 +363,11 @@ def _convert_listlike(arg, box, format, name=None, tz=tz):
                                                            tz=tz,
                                                            name=name)
                                 else:
-                                    stamps = [tslibs.Timestamp(res, tz=tz)
+                                    stamps = [tslib.Timestamp(res, tz=tz)
                                               for res in result]
                                     result = np.array(stamps, dtype=object)
                             else:
-                                stamps = [tslibs.Timestamp(res, tz=tz)
+                                stamps = [tslib.Timestamp(res, tz=tz)
                                           for res, tz in zip(result, tznames)]
                                 result = np.array(stamps, dtype=object)
                             return result
@@ -381,16 +382,17 @@ def _convert_listlike(arg, box, format, name=None, tz=tz):
                                                            tz=tzoffset,
                                                            name=name)
                                 else:
-                                    stamps = [tslibs.Timestamp(res,
-                                                               tzinfo=tzoffset)
-                                              for res, offset in result]
+                                    stamps = [tslib.Timestamp(res,
+                                                              tzinfo=tzoffset)
+                                              for res, offset in
+                                              zip(result, tzoffsets)]
                                     result = np.array(stamps, dtype=object)
                             else:
                                 stamps = []
                                 for res, offset in zip(result, tzoffsets):
                                     offset_mins = offset.total_seconds() / 60
                                     tzoffset = pytz.FixedOffset(offset_mins)
-                                    ts = tslibs.Timestamp(res, tzinfo=tzoffset)
+                                    ts = tslib.Timestamp(res, tzinfo=tzoffset)
                                     stamps.append(ts)
                                 result = np.array(stamps, dtype=object)
                             return result
diff --git a/pandas/tests/indexes/datetimes/test_tools.py b/pandas/tests/indexes/datetimes/test_tools.py
index 4fad75efe865ac..ddedc2c6b70994 100644
--- a/pandas/tests/indexes/datetimes/test_tools.py
+++ b/pandas/tests/indexes/datetimes/test_tools.py
@@ -184,7 +184,9 @@ def test_to_datetime_format_weeks(self, cache):
         for s, format, dt in data:
             assert to_datetime(s, format=format, cache=cache) == dt
 
-    @pytest.skipif(not PY3, reason="datetime.timezone not supported in PY2")
+    @pytest.mark.skipif(not PY3,
+                        reason="datetime.timezone not supported in PY2")
+    @pytest.mark.xfail(reason="GH #20257")
     def test_to_datetime_parse_timezone(self):
         from datetime import timezone
         # %Z parsing only
@@ -195,6 +197,17 @@ def test_to_datetime_parse_timezone(self):
         expected = pd.DatetimeIndex(expected_dates)
         tm.assert_index_equal(result, expected)
 
+        result = pd.to_datetime(dates, format=fmt, box=False)
+        expected = np.array(expected_dates, dtype=object)
+        tm.assert_numpy_array_equal(result, expected)
+
+        dates = ['2010-01-01 12:00:00 UTC', '2010-01-01 12:00:00 GMT']
+        result = pd.to_datetime(dates, format=fmt)
+        expected_dates = [pd.Timestamp('2010-01-01 12:00:00', tz='UTC'),
+                          pd.Timestamp('2010-01-01 12:00:00', tz='GMT')]
+        expected = np.array(expected_dates, dtype=object)
+        tm.assert_numpy_array_equal(result, expected)
+
         # %z parsing only
         dates = ['2010-01-01 12:00:00 +0100'] * 2
         fmt = '%Y-%m-%d %H:%M:%S %z'
@@ -204,17 +217,31 @@ def test_to_datetime_parse_timezone(self):
         expected = pd.DatetimeIndex(expected_dates)
         tm.assert_index_equal(result, expected)
 
+        result = pd.to_datetime(dates, format=fmt, box=False)
+        expected = np.array(expected_dates, dtype=object)
+        tm.assert_numpy_array_equal(result, expected)
+
+        dates = ['2010-01-01 12:00:00 +0100', '2010-01-01 12:00:00 -0100']
+        result = pd.to_datetime(dates, format=fmt)
+        expected_dates = [pd.Timestamp('2010-01-01 12:00:00',
+                                       tzinfo=pytz.FixedOffset(60)),
+                          pd.Timestamp('2010-01-01 12:00:00',
+                                       tzinfo=pytz.FixedOffset(-60))]
+        expected = np.array(expected_dates, dtype=object)
+        tm.assert_numpy_array_equal(result, expected)
+
         # %z and %Z parsing
         dates = ['2010-01-01 12:00:00 UTC +0100'] * 2
         fmt = '%Y-%m-%d %H:%M:%S %Z %z'
         result = pd.to_datetime(dates, format=fmt)
         tzinfo = timezone(timedelta(minutes=60), 'UTC')
-        expected_dates = [pd.Timestamp('2010-01-01 12:00:00', tzinfo=tzinfo)]
+        expected_dates = [pd.Timestamp('2010-01-01 13:00:00', tzinfo=tzinfo)]
         expected = np.array(expected_dates * 2, dtype=object)
         tm.assert_numpy_array_equal(result, expected)
 
         with pytest.raises(ValueError):
-            pd.to_datetime(dates, format=fmt, tz='US/Pacific')
+            pd.to_datetime(dates, format=fmt, utc=True)
+
 
 class TestToDatetime(object):
     def test_to_datetime_pydatetime(self):