diff --git a/nxontology/ontology.py b/nxontology/ontology.py
index 4a9b58b..6e1417a 100644
--- a/nxontology/ontology.py
+++ b/nxontology/ontology.py
@@ -29,8 +29,13 @@ class NXOntology(Freezable, Generic[Node]):
     Edges should go from general to more specific.
     """
 
-    def __init__(self, graph: nx.DiGraph | None = None):
+    def __init__(
+        self,
+        graph: nx.DiGraph | None = None,
+        node_info_class: type[Node_Info[Node]] = Node_Info,
+    ):
         self.graph = nx.DiGraph(graph)
+        self.node_info_class = node_info_class
         if graph is None:
             # Store the nxontology version that created the graph as metadata,
             # in case there are compatability issues in the future.
@@ -215,9 +220,9 @@ def node_info(self, node: Node) -> Node_Info[Node]:
         If frozen, cache node info in `self._node_info_cache`.
         """
         if not self.frozen:
-            return Node_Info(self, node)
+            return self.node_info_class(self, node)
         if node not in self._node_info_cache:
-            self._node_info_cache[node] = Node_Info(self, node)
+            self._node_info_cache[node] = self.node_info_class(self, node)
         return self._node_info_cache[node]
 
     @cache_on_frozen
diff --git a/nxontology/similarity.py b/nxontology/similarity.py
index 48c2298..3ef46f1 100644
--- a/nxontology/similarity.py
+++ b/nxontology/similarity.py
@@ -125,17 +125,17 @@ class SimilarityIC(Similarity[Node]):
 
     def __init__(
         self,
-        graph: NXOntology[Node],
+        nxo: NXOntology[Node],
         node_0: Node,
         node_1: Node,
         ic_metric: str = "intrinsic_ic_sanchez",
     ):
-        super().__init__(graph, node_0, node_1)
+        super().__init__(nxo, node_0, node_1)
 
-        if ic_metric not in Node_Info.ic_metrics:
+        if ic_metric not in nxo.node_info_class.ic_metrics:
             raise ValueError(
                 f"{ic_metric!r} is not a supported ic_metric. "
-                f"Choose from: {', '.join(Node_Info.ic_metrics)}."
+                f"Choose from: {', '.join(nxo.node_info_class.ic_metrics)}."
             )
         self.ic_metric = ic_metric
         self.ic_metric_scaled = f"{ic_metric}_scaled"
diff --git a/nxontology/tests/ontology_test.py b/nxontology/tests/ontology_test.py
index 3a67f75..c96a882 100644
--- a/nxontology/tests/ontology_test.py
+++ b/nxontology/tests/ontology_test.py
@@ -5,6 +5,7 @@
 import pytest
 
 from nxontology.exceptions import DuplicateError, NodeNotFound
+from nxontology.node import Node_Info
 from nxontology.ontology import NXOntology
 
 
@@ -151,3 +152,18 @@ def test_node_info_by_name() -> None:
 def test_node_info_not_found(metal_nxo_frozen: NXOntology[str]) -> None:
     with pytest.raises(NodeNotFound, match="not-a-metal not in graph"):
         metal_nxo_frozen.node_info("not-a-metal")
+
+
+def test_custom_node_info_class() -> None:
+    class CustomNodeInfo(Node_Info[str]):
+        @property
+        def custom_property(self) -> str:
+            return "custom"
+
+    nxo: NXOntology[str] = NXOntology(node_info_class=CustomNodeInfo)
+    nxo.add_node("a", name="a_name")
+    assert nxo.node_info("a").custom_property == "custom"  # type: ignore [attr-defined]
+    assert nxo.node_info_by_name("a_name").custom_property == "custom"  # type: ignore [attr-defined]
+    similarity = nxo.similarity("a", "a")
+    assert similarity.info_0.custom_property == "custom"  # type: ignore [attr-defined]
+    assert similarity.info_1.custom_property == "custom"  # type: ignore [attr-defined]