diff --git a/tests/operations/index.mjs b/tests/operations/index.mjs
index b25a2c2c..196a2a35 100644
--- a/tests/operations/index.mjs
+++ b/tests/operations/index.mjs
@@ -117,6 +117,7 @@ import "./tests/Magic.mjs";
 import "./tests/Media.mjs";
 import "./tests/MIMEDecoding.mjs";
 import "./tests/Modhex.mjs";
+import "./tests/ModularExponentiation.mjs";
 import "./tests/MorseCode.mjs";
 import "./tests/MS.mjs";
 import "./tests/MultipleBombe.mjs";
diff --git a/tests/operations/tests/ModularExponentiation.mjs b/tests/operations/tests/ModularExponentiation.mjs
new file mode 100644
index 00000000..4912530f
--- /dev/null
+++ b/tests/operations/tests/ModularExponentiation.mjs
@@ -0,0 +1,137 @@
+/**
+ * Modular Exponentiation tests.
+ *
+ * @author p-leriche [philip.leriche@cantab.net]
+ *
+ * @copyright Crown Copyright 2025
+ * @license Apache-2.0
+ */
+import TestRegister from "../../lib/TestRegister.mjs";
+
+TestRegister.addTests([
+    {
+        name: "Modular Exponentiation: basic example (2^10 mod 1000)",
+        input: "",
+        expectedOutput: "24",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: ["2", "1000", "10"],
+            },
+        ],
+    },
+    {
+        name: "Modular Exponentiation: small values (3^5 mod 7)",
+        input: "",
+        expectedOutput: "5",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: ["3", "7", "5"],
+            },
+        ],
+    },
+    {
+        name: "Modular Exponentiation: exponent zero",
+        input: "",
+        expectedOutput: "1",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: ["999", "100", "0"],
+            },
+        ],
+    },
+    {
+        name: "Modular Exponentiation: base one",
+        input: "",
+        expectedOutput: "1",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: ["1", "1000", "999"],
+            },
+        ],
+    },
+    {
+        name: "Modular Exponentiation: hexadecimal input",
+        input: "",
+        expectedOutput: "256",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: ["0x10", "1000", "0x2"],
+            },
+        ],
+    },
+    {
+        name: "Modular Exponentiation: using input field for base",
+        input: "5",
+        expectedOutput: "6",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: ["", "7", "3"],
+            },
+        ],
+    },
+    {
+        name: "Modular Exponentiation: using input field for exponent",
+        input: "4",
+        expectedOutput: "5",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: ["2", "11", ""],
+            },
+        ],
+    },
+    {
+        name: "Modular Exponentiation: RSA-like example (small)",
+        input: "",
+        expectedOutput: "561",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: ["123", "1000", "456"],
+            },
+        ],
+    },
+    {
+        name: "Modular Exponentiation: large base and exponent",
+        input: "",
+        expectedOutput: "560583526",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: ["123456789", "1000000007", "65537"],
+            },
+        ],
+    },
+    {
+        name: "Modular Exponentiation: crypto-sized numbers (RSA-2048 simulation)",
+        input: "",
+        expectedOutput: "1",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: [
+                    "12345678901234567890123456789012345678901234567890",
+                    "99999999999999999999999999999999999999999999999999",
+                    "0"
+                ],
+            },
+        ],
+    },
+    {
+        name: "Modular Exponentiation: Fermat's Little Theorem (a^(p-1) mod p = 1)",
+        input: "",
+        expectedOutput: "1",
+        recipeConfig: [
+            {
+                op: "Modular Exponentiation",
+                args: ["3", "11", "10"],
+            },
+        ],
+    },
+]);