diff --git a/src/lib/node.spec.ts b/src/lib/node.spec.ts
index e4d4705310..1b93a913eb 100644
--- a/src/lib/node.spec.ts
+++ b/src/lib/node.spec.ts
@@ -84,8 +84,6 @@ test('Nim-interop: js node subscribes to default waku topic (only checking js si
 
   const peerId = node.peerId.toB58String();
 
-  console.log(`js peer id: ${peerId}`);
-
   const localMultiaddr = node.multiaddrs.find((addr) =>
     addr.toString().match(/127\.0\.0\.1/)
   );
@@ -104,6 +102,40 @@ test('Nim-interop: js node subscribes to default waku topic (only checking js si
   t.true(subscribers.includes(nimPeerId));
 });
 
+test('Nim-interop: nim node sends message', async (t) => {
+  const node = await createNode();
+
+  const peerId = node.peerId.toB58String();
+
+  console.log(`js peer id: ${peerId}`);
+
+  const localMultiaddr = node.multiaddrs.find((addr) =>
+    addr.toString().match(/127\.0\.0\.1/)
+  );
+  const multiAddrWithId = localMultiaddr + '/p2p/' + peerId;
+
+  const nimWaku = new NimWaku();
+  await nimWaku.start({ staticnode: multiAddrWithId });
+
+  const wakuRelayNode = new WakuRelay(node.pubsub);
+  await wakuRelayNode.subscribe();
+
+  // Setup the promise before publishing to ensure the event is not missed
+  const promise = waitForNextData(node.pubsub);
+
+  const message = Message.fromString('This is a message.');
+
+  await delay(500);
+
+  await nimWaku.sendMessage(message);
+
+  await delay(1000);
+
+  const received = await promise;
+
+  t.true(received.isEqualTo(message));
+});
+
 function waitForNextData(pubsub: Pubsub): Promise<Message> {
   return new Promise((resolve) => {
     pubsub.once(TOPIC, resolve);
diff --git a/src/lib/waku_message.ts b/src/lib/waku_message.ts
index 114dd1e452..cc5ee9d93d 100644
--- a/src/lib/waku_message.ts
+++ b/src/lib/waku_message.ts
@@ -7,7 +7,7 @@ export class Message {
   public contentTopic: number;
   public version: number;
 
-  private constructor(private protobuf: WakuMessage) {
+  private constructor(public protobuf: WakuMessage) {
     this.protobuf = protobuf;
 
     const msg = protobuf.toObject();
@@ -27,7 +27,7 @@ export class Message {
     // This is the content topic commonly used at this time
     wakuMsg.setContentTopic(1);
 
-    wakuMsg.setPayload(Buffer.from(message));
+    wakuMsg.setPayload(message);
 
     return new Message(wakuMsg);
   }
diff --git a/src/test_utils/nim_waku.ts b/src/test_utils/nim_waku.ts
index 91ff0fde6d..c7c3ee1e8a 100644
--- a/src/test_utils/nim_waku.ts
+++ b/src/test_utils/nim_waku.ts
@@ -7,6 +7,9 @@ import Multiaddr from 'multiaddr';
 import multiaddr from 'multiaddr';
 import PeerId from 'peer-id';
 
+import { Message } from '../lib/waku_message';
+import { TOPIC } from '../lib/waku_relay';
+
 import waitForLine from './log_file';
 
 const openAsync = promisify(fs.open);
@@ -77,6 +80,37 @@ export class NimWaku {
     return res.result;
   }
 
+  async sendMessage(message: Message) {
+    this.checkProcess();
+
+    let payload;
+    if (typeof message.payload === 'string') {
+      payload = strToHex(message.payload);
+    } else {
+      payload = bufToHex(message.payload);
+    }
+
+    const rpcMessage = {
+      payload,
+      contentTopic: message.contentTopic,
+    };
+
+    const res = await this.rpcCall('post_waku_v2_relay_v1_message', [
+      TOPIC,
+      rpcMessage,
+    ]);
+
+    return res.result;
+  }
+
+  async messages() {
+    this.checkProcess();
+
+    const res = await this.rpcCall('get_waku_v2_relay_v1_messages', [TOPIC]);
+
+    return res.result;
+  }
+
   get peerId(): PeerId {
     return NIM_WAKU_PEER_ID;
   }
@@ -143,3 +177,27 @@ export function mergeArguments(args: Args): Args {
 
   return res;
 }
+
+// TODO: Test this
+function strToHex(str: string): string {
+  let hex: string;
+  try {
+    hex = unescape(encodeURIComponent(str))
+      .split('')
+      .map(function (v) {
+        return v.charCodeAt(0).toString(16).toUpperCase();
+      })
+      .join('');
+  } catch (e) {
+    hex = str;
+    console.log('invalid text input: ' + str);
+  }
+  return '0x' + hex;
+}
+
+// TODO: Test this
+function bufToHex(buffer: Uint8Array) {
+  return Array.prototype.map
+    .call(buffer, (x) => ('00' + x.toString(16)).slice(-2))
+    .join('');
+}