diff --git a/uttut/pipeline/ops/add_end_token.py b/uttut/pipeline/ops/add_end_token.py
new file mode 100644
index 0000000..2785148
--- /dev/null
+++ b/uttut/pipeline/ops/add_end_token.py
@@ -0,0 +1,64 @@
+from typing import List, Tuple
+
+from .base import Operator
+from .tokens import END_TOKEN
+from .add_sos_eos import AddSosEosAligner
+from ..edit import lst2lst
+from ..edit.replacement import ReplacementGroup
+
+
+class AddEndToken(Operator):
+
+    """
+    Add end token (<eos>) to a sequence.
+
+    E.g.
+    >>> from uttut.pipeline.ops.add_sos_eos import AddSosEos
+    >>> op = AddEndToken()
+    >>> output_seq, label_aligner = op.transform(
+        ['I', 'have', '10.7', 'dollars', '.'])
+    >>> output_labels = label_aligner.transform([1, 2, 3, 4, 5])
+    >>> output_seq
+    ['I', 'have', '10.7', 'dollars', '.', '<eos>']
+    >>> output_labels
+    [1, 2, 3, 4, 5, 0]
+    >>> label_aligner.inverse_transform(output_labels)
+    [1, 2, 3, 4, 5]
+
+    """
+
+    _input_type = list
+    _output_type = list
+
+    def __init__(self, end_token: str = END_TOKEN):
+        self.end_token = self._validate_end_token(end_token)
+
+    def _validate_end_token(self, end_token: str):
+        if end_token is None:
+            raise ValueError("The end token can not be None.")
+
+        if not isinstance(end_token, str):
+            raise TypeError("The end token should be a string.")
+
+        if len(end_token) == 0:
+            raise ValueError("The end token should not be an empty string.")
+
+        return end_token
+
+    def _transform(self, input_sequence: List[str]) -> Tuple[List[str], 'LabelAligner']:
+        forward_replacement_group = self._gen_forward_replacement_group(input_sequence)
+        output_sequence = lst2lst.apply(input_sequence, forward_replacement_group)
+
+        label_aligner = AddSosEosAligner(
+            input_sequence=input_sequence,
+            edit=forward_replacement_group,
+            output_length=len(output_sequence),
+        )
+        return output_sequence, label_aligner
+
+    def _gen_forward_replacement_group(self, input_lst: List[str]) -> ReplacementGroup:
+        seqlen = len(input_lst)
+        replacement_group = ReplacementGroup.add_all(
+            [(seqlen, seqlen, [self.end_token], 'add-end-token')],
+        )
+        return replacement_group
diff --git a/uttut/pipeline/ops/tests/test_add_end_token.py b/uttut/pipeline/ops/tests/test_add_end_token.py
new file mode 100644
index 0000000..9354d18
--- /dev/null
+++ b/uttut/pipeline/ops/tests/test_add_end_token.py
@@ -0,0 +1,71 @@
+import pytest
+
+from ..add_end_token import AddEndToken
+from ..tokens import END_TOKEN
+from .common_tests import OperatorTestTemplate, ParamTuple
+
+
+class TestAddEndToken(OperatorTestTemplate):
+
+    params = [
+        ParamTuple(
+            ['alvin', '喜歡', '吃', '榴槤'],
+            [1, 2, 3, 4],
+            ['alvin', '喜歡', '吃', '榴槤', '<eos>'],
+            [1, 2, 3, 4, 0],
+            'zh',
+        ),
+    ]
+
+    @pytest.fixture(scope='class')
+    def op(self):
+        return AddEndToken()
+
+    def test_not_equal(self, op):
+        custom_op = AddEndToken(end_token='custom_EOS')
+        assert custom_op != op
+
+
+@pytest.mark.parametrize(
+    "op, expected_configs",
+    [
+        pytest.param(
+            AddEndToken(),
+            {'end_token': END_TOKEN},
+            id="default",
+        ),
+        pytest.param(
+            AddEndToken('1'),
+            {'end_token': '1'},
+            id="no keywords",
+        ),
+
+    ],
+)
+def test_correct_configs(op, expected_configs):
+    assert op.configs == expected_configs
+
+
+@pytest.mark.parametrize(
+    "end_token, error",
+    [
+        pytest.param(
+            None,
+            ValueError,
+            id="The end token can not be None",
+        ),
+        pytest.param(
+            1,
+            TypeError,
+            id="wrong type of end token",
+        ),
+        pytest.param(
+            '',
+            ValueError,
+            id="empty string is not allowed.",
+        ),
+    ],
+)
+def test_invalid_end_token(end_token, error):
+    with pytest.raises(error):
+        AddEndToken(end_token)