diff --git a/comfy_extras/nodes_mask.py b/comfy_extras/nodes_mask.py
index 3fae7221f..530782cdb 100644
--- a/comfy_extras/nodes_mask.py
+++ b/comfy_extras/nodes_mask.py
@@ -262,7 +262,7 @@ class MaskComposite(IO.ComfyNode):
                 IO.Mask.Input("source"),
                 IO.Int.Input("x", default=0, min=0, max=nodes.MAX_RESOLUTION, step=1),
                 IO.Int.Input("y", default=0, min=0, max=nodes.MAX_RESOLUTION, step=1),
-                IO.Combo.Input("operation", options=["multiply", "add", "subtract", "and", "or", "xor"]),
+                IO.Combo.Input("operation", options=["multiply", "add", "subtract", "and", "or", "xor", "max", "min"], tooltip="How to combine the two masks. \"multiply\", \"add\", \"subtract\", \"max\" and \"min\" are arithmetic and preserve intermediate (feathered) mask values. \"and\", \"or\" and \"xor\" are boolean: they round each mask to 0 or 1 first, discarding any feathering. Use \"max\"/\"min\" for union/intersection of soft masks."),
             ],
             outputs=[IO.Mask.Output()],
         )
@@ -292,6 +292,10 @@ class MaskComposite(IO.ComfyNode):
             output[:, top:bottom, left:right] = torch.bitwise_or(destination_portion.round().bool(), source_portion.round().bool()).float()
         elif operation == "xor":
             output[:, top:bottom, left:right] = torch.bitwise_xor(destination_portion.round().bool(), source_portion.round().bool()).float()
+        elif operation == "max":
+            output[:, top:bottom, left:right] = torch.max(destination_portion, source_portion)
+        elif operation == "min":
+            output[:, top:bottom, left:right] = torch.min(destination_portion, source_portion)
 
         output = torch.clamp(output, 0.0, 1.0)
 
diff --git a/tests-unit/comfy_extras_test/nodes_mask_test.py b/tests-unit/comfy_extras_test/nodes_mask_test.py
new file mode 100644
index 000000000..a02032c3a
--- /dev/null
+++ b/tests-unit/comfy_extras_test/nodes_mask_test.py
@@ -0,0 +1,58 @@
+import pytest
+import torch
+from unittest.mock import patch, MagicMock
+
+mock_nodes = MagicMock()
+mock_nodes.MAX_RESOLUTION = 16384
+mock_server = MagicMock()
+
+with patch.dict("sys.modules", {"nodes": mock_nodes, "server": mock_server}):
+    from comfy_extras.nodes_mask import MaskComposite
+
+
+class TestMaskCompositeOperations:
+    @staticmethod
+    def _exec(destination, source, operation):
+        d = torch.tensor([[destination]])
+        s = torch.tensor([[source]])
+        return MaskComposite.execute(d, s, 0, 0, operation).result[0].flatten().tolist()
+
+    def test_max_is_union_of_soft_masks(self):
+        result = self._exec([0.0, 0.25, 0.75, 1.0], [0.5, 0.5, 0.5, 0.5], "max")
+        assert result == pytest.approx([0.5, 0.5, 0.75, 1.0])
+
+    def test_min_is_intersection_of_soft_masks(self):
+        result = self._exec([0.0, 0.25, 0.75, 1.0], [0.5, 0.5, 0.5, 0.5], "min")
+        assert result == pytest.approx([0.0, 0.25, 0.5, 0.5])
+
+    def test_max_preserves_intermediate_values(self):
+        # Unlike "or", max must not round feathered values to 0 or 1.
+        result = self._exec([0.25, 0.75], [0.0, 0.0], "max")
+        assert result == pytest.approx([0.25, 0.75])
+
+    def test_min_preserves_intermediate_values(self):
+        result = self._exec([0.25, 0.75], [1.0, 1.0], "min")
+        assert result == pytest.approx([0.25, 0.75])
+
+    def test_or_binarizes(self):
+        # Documents existing behaviour that motivates max/min.
+        result = self._exec([0.25, 0.75], [0.0, 0.0], "or")
+        assert result == pytest.approx([0.0, 1.0])
+
+    def test_max_is_commutative(self):
+        a = self._exec([0.3, 0.8], [0.6, 0.1], "max")
+        b = self._exec([0.6, 0.1], [0.3, 0.8], "max")
+        assert a == pytest.approx(b)
+
+    def test_min_is_commutative(self):
+        a = self._exec([0.3, 0.8], [0.6, 0.1], "min")
+        b = self._exec([0.6, 0.1], [0.3, 0.8], "min")
+        assert a == pytest.approx(b)
+
+    def test_max_with_empty_mask_is_identity(self):
+        result = self._exec([0.0, 0.4, 1.0], [0.0, 0.0, 0.0], "max")
+        assert result == pytest.approx([0.0, 0.4, 1.0])
+
+    def test_min_with_full_mask_is_identity(self):
+        result = self._exec([0.0, 0.4, 1.0], [1.0, 1.0, 1.0], "min")
+        assert result == pytest.approx([0.0, 0.4, 1.0])