diff --git a/src/SlashCommands.js b/src/SlashCommands.js
index a1364efbe1..55107db899 100644
--- a/src/SlashCommands.js
+++ b/src/SlashCommands.js
@@ -31,6 +31,7 @@ import MultiInviter from './utils/MultiInviter';
 import { linkifyAndSanitizeHtml } from './HtmlUtils';
 import QuestionDialog from "./components/views/dialogs/QuestionDialog";
 import WidgetUtils from "./utils/WidgetUtils";
+import {textToHtmlRainbow} from "./utils/colour";
 import Promise from "bluebird";
 
 class Command {
@@ -761,6 +762,26 @@ export const CommandMap = {
             return success();
         },
     }),
+
+    rainbow: new Command({
+        name: "rainbow",
+        description: _td("Sends the given message coloured as a rainbow"),
+        args: '<message>',
+        runFn: function(roomId, args) {
+            if (!args) return reject(this.getUserId());
+            return success(MatrixClientPeg.get().sendHtmlMessage(roomId, args, textToHtmlRainbow(args)));
+        },
+    }),
+
+    rainbowme: new Command({
+        name: "rainbowme",
+        description: _td("Sends the given emote coloured as a rainbow"),
+        args: '<message>',
+        runFn: function(roomId, args) {
+            if (!args) return reject(this.getUserId());
+            return success(MatrixClientPeg.get().sendHtmlEmote(roomId, args, textToHtmlRainbow(args)));
+        },
+    }),
 };
 /* eslint-enable babel/no-invalid-this */
 
diff --git a/src/i18n/strings/en_EN.json b/src/i18n/strings/en_EN.json
index 11680220df..6d91d999da 100644
--- a/src/i18n/strings/en_EN.json
+++ b/src/i18n/strings/en_EN.json
@@ -179,6 +179,8 @@
     "The signing key you provided matches the signing key you received from %(userId)s's device %(deviceId)s. Device marked as verified.": "The signing key you provided matches the signing key you received from %(userId)s's device %(deviceId)s. Device marked as verified.",
     "Displays action": "Displays action",
     "Forces the current outbound group session in an encrypted room to be discarded": "Forces the current outbound group session in an encrypted room to be discarded",
+    "Sends the given message coloured as a rainbow": "Sends the given message coloured as a rainbow",
+    "Sends the given emote coloured as a rainbow": "Sends the given emote coloured as a rainbow",
     "Unrecognised command:": "Unrecognised command:",
     "Reason": "Reason",
     "%(targetName)s accepted the invitation for %(displayName)s.": "%(targetName)s accepted the invitation for %(displayName)s.",
diff --git a/src/utils/colour.js b/src/utils/colour.js
new file mode 100644
index 0000000000..5d90bf0773
--- /dev/null
+++ b/src/utils/colour.js
@@ -0,0 +1,67 @@
+/*
+Copyright 2019 Michael Telatynski <7t3chguy@gmail.com>
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+export function hueToRGB(h, s, l) {
+    const c = s * (1 - Math.abs(2 * l - 1));
+    const x = c * (1 - Math.abs((h / 60) % 2 - 1));
+    const m = l - c / 2;
+
+    let r = 0;
+    let g = 0;
+    let b = 0;
+
+    if (0 <= h && h < 60) {
+        r = c;
+        g = x;
+        b = 0;
+    } else if (60 <= h && h < 120) {
+        r = x;
+        g = c;
+        b = 0;
+    } else if (120 <= h && h < 180) {
+        r = 0;
+        g = c;
+        b = x;
+    } else if (180 <= h && h < 240) {
+        r = 0;
+        g = x;
+        b = c;
+    } else if (240 <= h && h < 300) {
+        r = x;
+        g = 0;
+        b = c;
+    } else if (300 <= h && h < 360) {
+        r = c;
+        g = 0;
+        b = x;
+    }
+
+    return [Math.round((r + m) * 255), Math.round((g + m) * 255), Math.round((b + m) * 255)];
+}
+
+
+export function textToHtmlRainbow(str) {
+    const frequency = 360 / str.length;
+
+    return str.split("").map((c, i) => {
+        const [r, g, b] = hueToRGB(i * frequency, 1.0, 0.5);
+        return '<font color="#' +
+            r.toString(16).padStart(2, "0") +
+            g.toString(16).padStart(2, "0") +
+            b.toString(16).padStart(2, "0") +
+            '">' + c + '</font>';
+    }).join("");
+}