diff --git a/packages/message/__tests__/store/publish.test.ts b/packages/message/__tests__/store/publish.test.ts
index 44558e54..10fcf9ad 100644
--- a/packages/message/__tests__/store/publish.test.ts
+++ b/packages/message/__tests__/store/publish.test.ts
@@ -13,10 +13,16 @@ describe('Store message publish', () => {
     const { account } = ethereum.newAccount()
     const fileContent = readFileSync('./packages/message/__tests__/store/testFile.txt')
 
+    const extraFields: Record<string, unknown> = {
+      key1: 'value1',
+      key2: 123,
+    }
+
     const hash = await store.send({
       channel: 'TEST',
       account: account,
       fileObject: fileContent,
+      extraFields,
     })
 
     const response = await store.download(hash.content.item_hash)
@@ -25,6 +31,7 @@ describe('Store message publish', () => {
     const expected = 'y'
 
     expect(got).toBe(expected)
+    expect(hash.content.extra_fields).toEqual(extraFields)
   })
 
   it('should pin a file and retrieve it correctly', async () => {
diff --git a/packages/message/src/store/impl.ts b/packages/message/src/store/impl.ts
index a4704755..ac97905a 100644
--- a/packages/message/src/store/impl.ts
+++ b/packages/message/src/store/impl.ts
@@ -43,6 +43,7 @@ export class StoreMessageClient {
     channel,
     fileHash,
     fileObject,
+    extraFields,
     sync = false,
   }: RequireOnlyOne<StorePublishConfiguration, 'fileObject' | 'fileHash'>): Promise<StoreMessage> {
     if (!fileObject && !fileHash) throw new Error('You need to specify a File to upload or a Hash to pin.')
@@ -65,6 +66,7 @@ export class StoreMessageClient {
       item_type: storageEngine,
       item_hash: hash,
       time: timestamp,
+      extra_fields: extraFields,
     }
 
     const builtMessage = buildStoreMessage({
diff --git a/packages/message/src/store/types.ts b/packages/message/src/store/types.ts
index df35ecea..bb9cb18e 100644
--- a/packages/message/src/store/types.ts
+++ b/packages/message/src/store/types.ts
@@ -7,6 +7,7 @@ export type StoreContent = BaseContent & {
   size?: number
   content_type?: string
   ref?: string
+  extra_fields?: Record<string, unknown>
 }
 
 // -------- PIN ----------
@@ -44,7 +45,7 @@ export type StorePinConfiguration = {
  *
  * inlineRequested: If set to False, the Store message will be store on the same storageEngine you picked.
  *
- * apiServer:       The API server endpoint used to carry the request to the Aleph's network.
+ * extraFields:     Extra fields to add to the Store message.
  *
  * sync:            If true, the function will wait for the message to be confirmed by the API server.
  */