diff --git a/src/core/config/Categories.json b/src/core/config/Categories.json
index 4fac84c..e9fe339 100755
--- a/src/core/config/Categories.json
+++ b/src/core/config/Categories.json
@@ -86,6 +86,8 @@
             "Bifid Cipher Decode",
             "Affine Cipher Encode",
             "Affine Cipher Decode",
+            "A1Z26 Cipher Encode",
+            "A1Z26 Cipher Decode",
             "Atbash Cipher",
             "Substitute",
             "Derive PBKDF2 key",
diff --git a/src/core/operations/A1Z26CipherDecode.mjs b/src/core/operations/A1Z26CipherDecode.mjs
new file mode 100644
index 0000000..2a9f9ce
--- /dev/null
+++ b/src/core/operations/A1Z26CipherDecode.mjs
@@ -0,0 +1,63 @@
+/**
+ * @author Jarmo van Lenthe [github.com/jarmovanlenthe]
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import Utils from "../Utils";
+import {DELIM_OPTIONS} from "../lib/Delim";
+import OperationError from "../errors/OperationError";
+
+/**
+ * A1Z26 Cipher Decode operation
+ */
+class A1Z26CipherDecode extends Operation {
+
+    /**
+     * A1Z26CipherDecode constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "A1Z26 Cipher Decode";
+        this.module = "Ciphers";
+        this.description = "Converts alphabet order numbers into their corresponding  alphabet character.<br><br>e.g. <code>1</code> becomes <code>a</code> and <code>2</code> becomes <code>b</code>.";
+        this.infoURL = "";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Delimiter",
+                type: "option",
+                value: DELIM_OPTIONS
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const delim = Utils.charRep(args[0] || "Space");
+
+        if (input.length === 0) {
+            return [];
+        }
+
+        const bites = input.split(delim);
+        let latin1 = "";
+        for (let i = 0; i < bites.length; i++) {
+            if (bites[i] < 1 || bites[i] > 26) {
+                throw new OperationError("Error: all numbers must be between 1 and 26.");
+            }
+            latin1 += Utils.chr(parseInt(bites[i], 10) + 96);
+        }
+        return latin1;
+    }
+
+}
+
+export default A1Z26CipherDecode;
diff --git a/src/core/operations/A1Z26CipherEncode.mjs b/src/core/operations/A1Z26CipherEncode.mjs
new file mode 100644
index 0000000..d1202d8
--- /dev/null
+++ b/src/core/operations/A1Z26CipherEncode.mjs
@@ -0,0 +1,61 @@
+/**
+ * @author Jarmo van Lenthe [github.com/jarmovanlenthe]
+ * @copyright Crown Copyright 2018
+ * @license Apache-2.0
+ */
+
+import Operation from "../Operation";
+import Utils from "../Utils";
+import {DELIM_OPTIONS} from "../lib/Delim";
+
+/**
+ * A1Z26 Cipher Encode operation
+ */
+class A1Z26CipherEncode extends Operation {
+
+    /**
+     * A1Z26CipherEncode constructor
+     */
+    constructor() {
+        super();
+
+        this.name = "A1Z26 Cipher Encode";
+        this.module = "Ciphers";
+        this.description = "Converts alphabet characters into their corresponding alphabet order number.<br><br>e.g. <code>a</code> becomes <code>1</code> and <code>b</code> becomes <code>2</code>.<br><br>Non-alphabet characters are dropped.";
+        this.infoURL = "";
+        this.inputType = "string";
+        this.outputType = "string";
+        this.args = [
+            {
+                name: "Delimiter",
+                type: "option",
+                value: DELIM_OPTIONS
+            }
+        ];
+    }
+
+    /**
+     * @param {string} input
+     * @param {Object[]} args
+     * @returns {string}
+     */
+    run(input, args) {
+        const delim = Utils.charRep(args[0] || "Space");
+        let output = "";
+
+        const sanitizedinput = input.toLowerCase(),
+            charcode = Utils.strToCharcode(sanitizedinput);
+
+        for (let i = 0; i < charcode.length; i++) {
+            const ordinal = charcode[i] - 96;
+
+            if (ordinal > 0 && ordinal <= 26) {
+                output += ordinal.toString(10) + delim;
+            }
+        }
+        return output.slice(0, -delim.length);
+    }
+
+}
+
+export default A1Z26CipherEncode;
diff --git a/test/tests/operations/Ciphers.mjs b/test/tests/operations/Ciphers.mjs
index fdc98a3..a46f50a 100644
--- a/test/tests/operations/Ciphers.mjs
+++ b/test/tests/operations/Ciphers.mjs
@@ -110,6 +110,39 @@ TestRegister.addTests([
             }
         ],
     },
+    {
+        name: "A1Z26 Encode: normal",
+        input: "This is the test sentence.",
+        expectedOutput: "20 8 9 19 9 19 20 8 5 20 5 19 20 19 5 14 20 5 14 3 5",
+        recipeConfig: [
+            {
+                op: "A1Z26 Cipher Encode",
+                args: ["Space"]
+            }
+        ],
+    },
+    {
+        name: "A1Z26 Decode: normal",
+        input: "20 8 9 19 9 19 20 8 5 20 5 19 20 19 5 14 20 5 14 3 5",
+        expectedOutput: "thisisthetestsentence",
+        recipeConfig: [
+            {
+                op: "A1Z26 Cipher Decode",
+                args: ["Space"]
+            }
+        ],
+    },
+    {
+        name: "A1Z26 Decode: error",
+        input: "20 8 9 27",
+        expectedOutput: "Error: all numbers must be between 1 and 26.",
+        recipeConfig: [
+            {
+                op: "A1Z26 Cipher Decode",
+                args: ["Space"]
+            }
+        ],
+    },
     {
         name: "Atbash: no input",
         input: "",