diff --git a/lib/types/crypto-types.js b/lib/types/crypto-types.js
--- a/lib/types/crypto-types.js
+++ b/lib/types/crypto-types.js
@@ -2,6 +2,7 @@
 
 import t, { type TInterface } from 'tcomb';
 
+import type { OlmSessionInitializationInfo } from './request-types.js';
 import { type AuthMetadata } from '../shared/identity-client-context.js';
 import { tShape } from '../utils/validation-utils.js';
 
@@ -130,6 +131,10 @@
     contentIdentityKeys: OLMIdentityKeys,
     initialEncryptedContent: string,
   ) => Promise<string>,
+  +contentOutboundSessionCreator: (
+    contentIdentityKeys: OLMIdentityKeys,
+    contentInitializationInfo: OlmSessionInitializationInfo,
+  ) => Promise<string>,
   +getOneTimeKeys: (numberOfKeys: number) => Promise<OneTimeKeysResultValues>,
   +validateAndUploadPrekeys: (authMetadata: AuthMetadata) => Promise<void>,
 };
diff --git a/lib/utils/__mocks__/config.js b/lib/utils/__mocks__/config.js
--- a/lib/utils/__mocks__/config.js
+++ b/lib/utils/__mocks__/config.js
@@ -17,6 +17,7 @@
     encrypt: jest.fn(),
     decrypt: jest.fn(),
     contentInboundSessionCreator: jest.fn(),
+    contentOutboundSessionCreator: jest.fn(),
     getOneTimeKeys: jest.fn(),
     validateAndUploadPrekeys: jest.fn(),
   },
diff --git a/native/crypto/olm-api.js b/native/crypto/olm-api.js
--- a/native/crypto/olm-api.js
+++ b/native/crypto/olm-api.js
@@ -7,6 +7,7 @@
   OlmAPI,
   OLMIdentityKeys,
 } from 'lib/types/crypto-types';
+import type { OlmSessionInitializationInfo } from 'lib/types/request-types.js';
 
 import { commCoreModule } from '../native-modules.js';
 
@@ -30,6 +31,24 @@
       contentIdentityKeys.ed25519,
     );
   },
+  async contentOutboundSessionCreator(
+    contentIdentityKeys: OLMIdentityKeys,
+    contentInitializationInfo: OlmSessionInitializationInfo,
+  ): Promise<string> {
+    const { prekey, prekeySignature, oneTimeKey } = contentInitializationInfo;
+    const identityKeys = JSON.stringify({
+      curve25519: contentIdentityKeys.curve25519,
+      ed25519: contentIdentityKeys.ed25519,
+    });
+
+    return commCoreModule.initializeContentOutboundSession(
+      identityKeys,
+      prekey,
+      prekeySignature,
+      oneTimeKey,
+      contentIdentityKeys.ed25519,
+    );
+  },
   async getOneTimeKeys(numberOfKeys: number): Promise<OneTimeKeysResultValues> {
     const { contentOneTimeKeys, notificationsOneTimeKeys } =
       await commCoreModule.getOneTimeKeys(numberOfKeys);
diff --git a/web/crypto/olm-api.js b/web/crypto/olm-api.js
--- a/web/crypto/olm-api.js
+++ b/web/crypto/olm-api.js
@@ -54,6 +54,7 @@
   encrypt: proxyToWorker('encrypt'),
   decrypt: proxyToWorker('decrypt'),
   contentInboundSessionCreator: proxyToWorker('contentInboundSessionCreator'),
+  contentOutboundSessionCreator: proxyToWorker('contentOutboundSessionCreator'),
   getOneTimeKeys: proxyToWorker('getOneTimeKeys'),
   validateAndUploadPrekeys: proxyToWorker('validateAndUploadPrekeys'),
 };
diff --git a/web/shared-worker/worker/worker-crypto.js b/web/shared-worker/worker/worker-crypto.js
--- a/web/shared-worker/worker/worker-crypto.js
+++ b/web/shared-worker/worker/worker-crypto.js
@@ -3,6 +3,7 @@
 import olm from '@commapp/olm';
 import uuid from 'uuid';
 
+import { initialEncryptedMessageContent } from 'lib/shared/crypto-utils.js';
 import {
   olmEncryptedMessageTypes,
   type OLMIdentityKeys,
@@ -17,6 +18,7 @@
   IdentityNewDeviceKeyUpload,
   IdentityExistingDeviceKeyUpload,
 } from 'lib/types/identity-service-types.js';
+import type { OlmSessionInitializationInfo } from 'lib/types/request-types.js';
 import { entries } from 'lib/utils/objects.js';
 import {
   retrieveAccountKeysSet,
@@ -389,6 +391,33 @@
 
     return initialEncryptedMessage;
   },
+  async contentOutboundSessionCreator(
+    contentIdentityKeys: OLMIdentityKeys,
+    contentInitializationInfo: OlmSessionInitializationInfo,
+  ): Promise<string> {
+    if (!cryptoStore) {
+      throw new Error('Crypto account not initialized');
+    }
+    const { contentAccount, contentSessions } = cryptoStore;
+
+    const session = new olm.Session();
+    session.create_outbound(
+      contentAccount,
+      contentIdentityKeys.curve25519,
+      contentIdentityKeys.ed25519,
+      contentInitializationInfo.prekey,
+      contentInitializationInfo.prekeySignature,
+      contentInitializationInfo.oneTimeKey,
+    );
+    const { body: initialContentEncryptedMessage } = session.encrypt(
+      JSON.stringify(initialEncryptedMessageContent),
+    );
+
+    contentSessions[contentIdentityKeys.ed25519] = session;
+    persistCryptoStore();
+
+    return initialContentEncryptedMessage;
+  },
   async getOneTimeKeys(numberOfKeys: number): Promise<OneTimeKeysResultValues> {
     if (!cryptoStore) {
       throw new Error('Crypto account not initialized');