diff --git a/lib/shared/dm-ops/dm-op-specs.js b/lib/shared/dm-ops/dm-op-specs.js
--- a/lib/shared/dm-ops/dm-op-specs.js
+++ b/lib/shared/dm-ops/dm-op-specs.js
@@ -12,6 +12,7 @@
 import { leaveThreadSpec } from './leave-thread-spec.js';
 import { removeMembersSpec } from './remove-members-spec.js';
 import { sendEditMessageSpec } from './send-edit-message-spec.js';
+import { sendMultimediaMessageSpec } from './send-multimedia-message-spec.js';
 import { sendReactionMessageSpec } from './send-reaction-message-spec.js';
 import { sendTextMessageSpec } from './send-text-message-spec.js';
 import { type DMOperationType, dmOperationTypes } from '../../types/dm-ops.js';
@@ -22,6 +23,7 @@
   [dmOperationTypes.CREATE_THREAD]: createThreadSpec,
   [dmOperationTypes.CREATE_SIDEBAR]: createSidebarSpec,
   [dmOperationTypes.SEND_TEXT_MESSAGE]: sendTextMessageSpec,
+  [dmOperationTypes.SEND_MULTIMEDIA_MESSAGE]: sendMultimediaMessageSpec,
   [dmOperationTypes.SEND_REACTION_MESSAGE]: sendReactionMessageSpec,
   [dmOperationTypes.SEND_EDIT_MESSAGE]: sendEditMessageSpec,
   [dmOperationTypes.ADD_MEMBERS]: addMembersSpec,
diff --git a/lib/shared/dm-ops/send-multimedia-message-spec.js b/lib/shared/dm-ops/send-multimedia-message-spec.js
new file mode 100644
--- /dev/null
+++ b/lib/shared/dm-ops/send-multimedia-message-spec.js
@@ -0,0 +1,67 @@
+// @flow
+
+import type {
+  DMOperationSpec,
+  ProcessDMOperationUtilities,
+} from './dm-op-spec.js';
+import type { DMSendMultimediaMessageOperation } from '../../types/dm-ops.js';
+import { messageTypes } from '../../types/message-types-enum.js';
+import type { MediaMessageData } from '../../types/messages/media.js';
+import type { ClientUpdateInfo } from '../../types/update-types.js';
+import { rawMessageInfoFromMessageData } from '../message-utils.js';
+
+function createMessageDataFromDMOperation(
+  dmOperation: DMSendMultimediaMessageOperation,
+): MediaMessageData {
+  const { threadID, creatorID, time, media } = dmOperation;
+  return {
+    type: messageTypes.MULTIMEDIA,
+    threadID,
+    creatorID,
+    time,
+    media,
+  };
+}
+
+const sendMultimediaMessageSpec: DMOperationSpec<DMSendMultimediaMessageOperation> =
+  Object.freeze({
+    notificationsCreationData: async (
+      dmOperation: DMSendMultimediaMessageOperation,
+    ) => {
+      const messageData = createMessageDataFromDMOperation(dmOperation);
+      return { messageDatas: [messageData] };
+    },
+    processDMOperation: async (
+      dmOperation: DMSendMultimediaMessageOperation,
+    ) => {
+      const { messageID } = dmOperation;
+      const messageData = createMessageDataFromDMOperation(dmOperation);
+      const rawMessageInfos = [
+        rawMessageInfoFromMessageData(messageData, messageID),
+      ];
+      const updateInfos: Array<ClientUpdateInfo> = [];
+      return {
+        rawMessageInfos,
+        updateInfos,
+      };
+    },
+    canBeProcessed(
+      dmOperation: DMSendMultimediaMessageOperation,
+      viewerID: string,
+      utilities: ProcessDMOperationUtilities,
+    ) {
+      if (utilities.threadInfos[dmOperation.threadID]) {
+        return { isProcessingPossible: true };
+      }
+      return {
+        isProcessingPossible: false,
+        reason: {
+          type: 'missing_thread',
+          threadID: dmOperation.threadID,
+        },
+      };
+    },
+    supportsAutoRetry: false,
+  });
+
+export { sendMultimediaMessageSpec };
diff --git a/lib/types/dm-ops.js b/lib/types/dm-ops.js
--- a/lib/types/dm-ops.js
+++ b/lib/types/dm-ops.js
@@ -3,6 +3,7 @@
 import t, { type TInterface, type TUnion } from 'tcomb';
 
 import { clientAvatarValidator, type ClientAvatar } from './avatar-types.js';
+import { type Media, mediaValidator } from './media-types.js';
 import type { RawMessageInfo } from './message-types.js';
 import type { NotificationsCreationData } from './notif-types.js';
 import type { OutboundP2PMessage } from './sqlite-types.js';
@@ -28,6 +29,7 @@
   CREATE_THREAD: 'create_thread',
   CREATE_SIDEBAR: 'create_sidebar',
   SEND_TEXT_MESSAGE: 'send_text_message',
+  SEND_MULTIMEDIA_MESSAGE: 'send_multimedia_message',
   SEND_REACTION_MESSAGE: 'send_reaction_message',
   SEND_EDIT_MESSAGE: 'send_edit_message',
   ADD_MEMBERS: 'add_members',
@@ -155,6 +157,24 @@
     text: t.String,
   });
 
+export type DMSendMultimediaMessageOperation = {
+  +type: 'send_multimedia_message',
+  +threadID: string,
+  +creatorID: string,
+  +time: number,
+  +messageID: string,
+  +media: $ReadOnlyArray<Media>,
+};
+export const dmSendMultimediaMessageOperationValidator: TInterface<DMSendMultimediaMessageOperation> =
+  tShape<DMSendMultimediaMessageOperation>({
+    type: tString(dmOperationTypes.SEND_MULTIMEDIA_MESSAGE),
+    threadID: t.String,
+    creatorID: tUserID,
+    time: t.Number,
+    messageID: t.String,
+    media: t.list(mediaValidator),
+  });
+
 export type DMSendReactionMessageOperation = {
   +type: 'send_reaction_message',
   +threadID: string,
@@ -350,6 +370,7 @@
   | DMCreateThreadOperation
   | DMCreateSidebarOperation
   | DMSendTextMessageOperation
+  | DMSendMultimediaMessageOperation
   | DMSendReactionMessageOperation
   | DMSendEditMessageOperation
   | DMAddMembersOperation
@@ -364,6 +385,7 @@
   dmCreateThreadOperationValidator,
   dmCreateSidebarOperationValidator,
   dmSendTextMessageOperationValidator,
+  dmSendMultimediaMessageOperationValidator,
   dmSendReactionMessageOperationValidator,
   dmSendEditMessageOperationValidator,
   dmAddMembersOperationValidator,