diff --git a/CHANGES.rst b/CHANGES.rst
index ab499ff8..b2e4f9b3 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -12,6 +12,7 @@ Improvements
 
 Bug fixes
 ^^^^^^^^^
+* GH248 Fix an issue causing a ValueError to be raised when using `dask_index_on` on non-integer columns
 * GH255 Fix an issue causing the python interpreter to shut down when reading an
   empty file (see also https://issues.apache.org/jira/browse/ARROW-8142)
 
diff --git a/asv_bench/benchmarks/index.py b/asv_bench/benchmarks/index.py
index 44b1eafd..7ee7b92c 100644
--- a/asv_bench/benchmarks/index.py
+++ b/asv_bench/benchmarks/index.py
@@ -80,6 +80,9 @@ def time_as_series_partitions_as_index(
     ):
         self.ktk_index.as_flat_series(partitions_as_index=True)
 
+    def time_observed_values(self, number_values, number_partitions, arrow_type):
+        self.ktk_index.observed_values()
+
 
 class SerializeIndex(IndexBase):
     timeout = 180
diff --git a/kartothek/core/index.py b/kartothek/core/index.py
index bdb68472..a1b6f34a 100644
--- a/kartothek/core/index.py
+++ b/kartothek/core/index.py
@@ -132,15 +132,13 @@ def __repr__(self) -> str:
             class_=type(self).__name__, attrs=", ".join(repr_str)
         )
 
-    def observed_values(self) -> np.array:
+    def observed_values(self, date_as_object=True) -> np.array:
         """
         Return an array of all observed values
         """
-        return np.fromiter(
-            (self.normalize_value(self.dtype, x) for x in self.index_dct.keys()),
-            count=len(self.index_dct),
-            dtype=self.dtype.to_pandas_dtype(),
-        )
+        keys = np.array(list(self.index_dct.keys()))
+        labeled_array = pa.array(keys, type=self.dtype)
+        return np.array(labeled_array.to_pandas(date_as_object=date_as_object))
 
     @staticmethod
     def normalize_value(dtype: pa.DataType, value: Any) -> Any:
diff --git a/tests/core/test_index.py b/tests/core/test_index.py
index 75f48df8..c11cc1b7 100644
--- a/tests/core/test_index.py
+++ b/tests/core/test_index.py
@@ -14,6 +14,7 @@
 from hypothesis import assume, given
 from pandas.testing import assert_series_equal
 
+from kartothek.core._compat import ARROW_LARGER_EQ_0150
 from kartothek.core.index import ExplicitSecondaryIndex, IndexBase, merge_indices
 from kartothek.core.testing import get_numpy_array_strategy
 
@@ -472,6 +473,50 @@ def test_index_raises_null_dtype():
     assert str(exc.value) == "Indices w/ null/NA type are not supported"
 
 
+@pytest.mark.parametrize(
+    "dtype,value",
+    [
+        (pa.bool_(), True),
+        (pa.int64(), 1),
+        (pa.float64(), 1.1),
+        (pa.binary(), b"x"),
+        (pa.string(), "x"),
+        (pa.timestamp("ns"), pd.Timestamp("2018-01-01").to_datetime64()),
+        (pa.date32(), datetime.date(2018, 1, 1)),
+        pytest.param(
+            pa.timestamp("ns", tz=pytz.timezone("Europe/Berlin")),
+            pd.Timestamp("2018-01-01", tzinfo=pytz.timezone("Europe/Berlin")),
+            marks=pytest.mark.xfail(
+                not ARROW_LARGER_EQ_0150,
+                reason="Timezone reoundtrips not supported in older versions",
+            ),
+        ),
+    ],
+)
+def test_observed_values_plain(dtype, value):
+    ind = ExplicitSecondaryIndex(
+        column="col", dtype=dtype, index_dct={value: ["part_label"]}
+    )
+    observed = ind.observed_values()
+    assert len(observed) == 1
+    assert list(observed) == [value]
+
+
+@pytest.mark.parametrize("date_as_object", [None, True, False])
+def test_observed_values_date_as_object(date_as_object):
+    value = datetime.date(2020, 1, 1)
+    ind = ExplicitSecondaryIndex(
+        column="col", dtype=pa.date32(), index_dct={value: ["part_label"]}
+    )
+    observed = ind.observed_values(date_as_object=date_as_object)
+    if date_as_object:
+        expected = value
+    else:
+        expected = pd.Timestamp(value).to_datetime64()
+    assert len(observed) == 1
+    assert observed[0] == expected
+
+
 @pytest.mark.parametrize(
     "dtype,value,expected",
     [
diff --git a/tests/io/dask/dataframe/test_read.py b/tests/io/dask/dataframe/test_read.py
index 752d7462..542b12a7 100644
--- a/tests/io/dask/dataframe/test_read.py
+++ b/tests/io/dask/dataframe/test_read.py
@@ -10,6 +10,7 @@
 from pandas import testing as pdt
 from pandas.testing import assert_frame_equal
 
+from kartothek.core.testing import get_dataframe_not_nested
 from kartothek.io.dask.dataframe import read_dataset_as_ddf
 from kartothek.io.eager import store_dataframes_as_dataset
 from kartothek.io.testing.read import *  # noqa
@@ -169,6 +170,34 @@ def test_reconstruct_dask_index(store_factory, index_type, monkeypatch):
     assert_frame_equal(ddf_expected_simple.compute(), ddf.compute())
 
 
+@pytest.fixture()
+def setup_reconstruct_dask_index_types(store_factory, df_not_nested):
+    indices = list(df_not_nested.columns)
+    indices.remove("null")
+    return store_dataframes_as_dataset(
+        store=store_factory,
+        dataset_uuid="dataset_uuid",
+        dfs=[df_not_nested],
+        secondary_indices=indices,
+    )
+
+
+@pytest.mark.parametrize("col", get_dataframe_not_nested().columns)
+def test_reconstruct_dask_index_types(
+    store_factory, setup_reconstruct_dask_index_types, col
+):
+    if col == "null":
+        pytest.xfail(reason="Cannot index null column")
+    ddf = read_dataset_as_ddf(
+        dataset_uuid=setup_reconstruct_dask_index_types.uuid,
+        store=store_factory,
+        table="table",
+        dask_index_on=col,
+    )
+    assert ddf.known_divisions
+    assert ddf.index.name == col
+
+
 def test_reconstruct_dask_index_sorting(store_factory, monkeypatch):
 
     # Make sure we're not shuffling anything