diff --git a/CHANGELOG.md b/CHANGELOG.md
index 222b1a79..2cd56ddc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,7 +8,8 @@
   * new option in room configuration to set the slow mode duration (new prosody module mod_muc_slow_mode).
   * default duration is configurable in channel's chat rooms options.
   * backend rejects messages when the slow mode is not respected.
-  * frontend: display an infobox when slow mode is active.
+  * front-end: display an infobox when slow mode is active.
+  * front-end: disable the message field during the slow mode duration.
 
 ### Minor changes and fixes
 
diff --git a/conversejs/lib/slow-mode/plugin.ts b/conversejs/lib/slow-mode/plugin.ts
index 6f5a58bf..3c923656 100644
--- a/conversejs/lib/slow-mode/plugin.ts
+++ b/conversejs/lib/slow-mode/plugin.ts
@@ -7,8 +7,42 @@ export const slowModePlugin = {
   dependencies: ['converse-muc', 'converse-muc-views'],
   async initialize (this: any) {
     const _converse = this._converse
-    _converse.api.listen.on('chatRoomInitialized', function (this: any, _model: any): void {
-      // TODO: disable the textarea after each new message, for X seconds.
+    _converse.api.listen.on('sendMessage', function (this: any, options: any): void {
+      // disabling the message form/textarea after each new message, for X seconds.
+      const { chatbox } = options
+
+      // bypass for moderators.
+      const self = chatbox.getOwnOccupant()
+      if (self.isModerator()) {
+        return
+      }
+
+      const slowModeDuration = parseInt(chatbox?.config?.get('slow_mode_duration'))
+      if (!(slowModeDuration > 0)) { // undefined, NaN, ...  are not considered > 0.
+        return
+      }
+
+      console.log(`Slow mode is enabled, disabling the message field for ${slowModeDuration} seconds.`)
+      // FIXME: we should search the chat-textarea related to chatbox.
+      // I did not find how to get it. As for now there is only one chatbox, we can ignore.
+      // FIXME: we disable the field after 100ms, because otherwise ConverseJS will re-enable it before.
+      setTimeout(() => {
+        document.querySelectorAll('.chat-textarea').forEach((textarea) => {
+          // FIXME: field could be enabled by something else (another event in ConverseJS).
+          // This is not very important: the server will reject messages anyway.
+
+          textarea.classList.add('disabled')
+          textarea.setAttribute('disabled', 'disabled')
+          // Note: we are adding a 100ms delay.
+          // To minimize the risk that user can send a message before the server will accept it
+          // (if the first message lagged for example)
+          setTimeout(() => {
+            textarea.classList.remove('disabled')
+            textarea.removeAttribute('disabled');
+            (textarea as HTMLTextAreaElement).focus()
+          }, slowModeDuration * 1000 + 100)
+        })
+      }, 100)
     })
   }
 }