diff --git a/test/pycardano/test_address.py b/test/pycardano/test_address.py
index 0ee21e49..e827f1b1 100644
--- a/test/pycardano/test_address.py
+++ b/test/pycardano/test_address.py
@@ -1,3 +1,4 @@
+import os
 import tempfile
 
 import pytest
@@ -219,7 +220,14 @@ def test_save_load_address():
     address_string = "addr_test1vr2p8st5t5cxqglyjky7vk98k7jtfhdpvhl4e97cezuhn0cqcexl7"
     address = Address.from_primitive(address_string)
 
-    with tempfile.NamedTemporaryFile() as f:
-        address.save(f.name)
-        loaded_address = Address.load(f.name)
+    # On Windows, NamedTemporaryFile keeps the file locked while open, so
+    # save() cannot open it for writing. Use delete=False and close the handle
+    # first, then clean up manually afterward.
+    with tempfile.NamedTemporaryFile(delete=False) as f:
+        tmp_path = f.name
+    try:
+        address.save(tmp_path)
+        loaded_address = Address.load(tmp_path)
         assert address == loaded_address
+    finally:
+        os.unlink(tmp_path)
diff --git a/test/pycardano/test_key.py b/test/pycardano/test_key.py
index 9d9384be..21c539e0 100644
--- a/test/pycardano/test_key.py
+++ b/test/pycardano/test_key.py
@@ -1,4 +1,5 @@
 import json
+import os
 import pathlib
 import tempfile
 
@@ -216,25 +217,42 @@ def test_stake_pool_key_load():
 
 
 def test_key_save():
-    with tempfile.NamedTemporaryFile() as f:
-        SK.save(f.name)
-        sk = PaymentSigningKey.load(f.name)
+    # On Windows, NamedTemporaryFile keeps the file locked while open.
+    # Use delete=False and close the handle first, then clean up manually.
+    with tempfile.NamedTemporaryFile(delete=False) as f:
+        tmp_path = f.name
+    try:
+        SK.save(tmp_path)
+        sk = PaymentSigningKey.load(tmp_path)
         assert SK == sk
+    finally:
+        os.unlink(tmp_path)
 
 
 def test_key_save_invalid_address():
-    with tempfile.NamedTemporaryFile() as f:
-        SK.save(f.name)
+    with tempfile.NamedTemporaryFile(delete=False) as f:
+        tmp_path = f.name
+    try:
+        SK.save(tmp_path)
         with pytest.raises(IOError):
-            VK.save(f.name)
+            VK.save(tmp_path)
+    finally:
+        os.unlink(tmp_path)
 
 
 def test_stake_pool_key_save():
-    with tempfile.NamedTemporaryFile() as skf, tempfile.NamedTemporaryFile() as vkf:
-        SPSK.save(skf.name)
-        sk = StakePoolSigningKey.load(skf.name)
-        SPVK.save(vkf.name)
-        vk = StakePoolSigningKey.load(vkf.name)
+    with tempfile.NamedTemporaryFile(delete=False) as skf:
+        sk_path = skf.name
+    with tempfile.NamedTemporaryFile(delete=False) as vkf:
+        vk_path = vkf.name
+    try:
+        SPSK.save(sk_path)
+        sk = StakePoolSigningKey.load(sk_path)
+        SPVK.save(vk_path)
+        vk = StakePoolSigningKey.load(vk_path)
+    finally:
+        os.unlink(sk_path)
+        os.unlink(vk_path)
     assert SPSK == sk
     assert SPVK == vk
 
diff --git a/test/pycardano/test_serialization.py b/test/pycardano/test_serialization.py
index a4352f5c..9a8c0ed9 100644
--- a/test/pycardano/test_serialization.py
+++ b/test/pycardano/test_serialization.py
@@ -1,4 +1,5 @@
 import json
+import os
 import tempfile
 from collections import defaultdict, deque
 from copy import deepcopy
@@ -1047,13 +1048,17 @@ def to_shallow_primitive(self) -> Union[Primitive, CBORSerializable]:
     assert test1_json["description"] == "Test Description"
     assert test1_json["cborHex"] == test1.to_cbor_hex()
 
-    with tempfile.NamedTemporaryFile() as f:
-        test1.save(f.name)
-        loaded = Test1.load(f.name)
+    with tempfile.NamedTemporaryFile(delete=False) as f:
+        tmp_path = f.name
+    try:
+        test1.save(tmp_path)
+        loaded = Test1.load(tmp_path)
         assert test1 == loaded
 
         with pytest.raises(IOError):
-            test1.save(f.name)
+            test1.save(tmp_path)
+    finally:
+        os.unlink(tmp_path)
 
 
 def test_ordered_set_as_key_in_dict():
diff --git a/test/pycardano/test_transaction.py b/test/pycardano/test_transaction.py
index 0beb8631..ec0c0f52 100644
--- a/test/pycardano/test_transaction.py
+++ b/test/pycardano/test_transaction.py
@@ -1,3 +1,4 @@
+import os
 import tempfile
 from dataclasses import dataclass
 from fractions import Fraction
@@ -265,10 +266,14 @@ def test_transaction_save_load():
     )
     tx = Transaction.from_cbor(tx_cbor)
 
-    with tempfile.NamedTemporaryFile() as f:
-        tx.save(f.name)
-        loaded_tx = Transaction.load(f.name)
+    with tempfile.NamedTemporaryFile(delete=False) as f:
+        tmp_path = f.name
+    try:
+        tx.save(tmp_path)
+        loaded_tx = Transaction.load(tmp_path)
         assert tx == loaded_tx
+    finally:
+        os.unlink(tmp_path)
 
 
 def test_multi_asset():
diff --git a/test/pycardano/test_witness.py b/test/pycardano/test_witness.py
index b4291034..d2a3979c 100644
--- a/test/pycardano/test_witness.py
+++ b/test/pycardano/test_witness.py
@@ -1,4 +1,5 @@
 import json
+import os
 import tempfile
 
 from pycardano import (
@@ -19,12 +20,16 @@ def test_witness_save_load():
         signature=sk.sign(b"test"),
     )
 
-    with tempfile.NamedTemporaryFile() as f:
-        witness.save(f.name)
-        loaded_witness = VerificationKeyWitness.load(f.name)
+    with tempfile.NamedTemporaryFile(delete=False) as f:
+        tmp_path = f.name
+    try:
+        witness.save(tmp_path)
+        loaded_witness = VerificationKeyWitness.load(tmp_path)
         assert witness == loaded_witness
 
         assert witness != vk
+    finally:
+        os.unlink(tmp_path)
 
 
 def test_redeemer_decode():