diff --git a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt
index c92658f7e8..ce20b160ae 100644
--- a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt
+++ b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt
@@ -27,6 +27,7 @@ import io.element.android.features.messages.impl.timeline.model.virtual.aTimelin
 import io.element.android.libraries.designsystem.components.avatar.AvatarData
 import io.element.android.libraries.designsystem.components.avatar.AvatarSize
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.timeline.MatrixTimeline
 import io.element.android.libraries.matrix.api.timeline.item.TimelineItemDebugInfo
@@ -102,7 +103,7 @@ fun aTimelineItemDaySeparator(): TimelineItem.Virtual {
 
 internal fun aTimelineItemEvent(
     eventId: EventId = EventId("\$" + Random.nextInt().toString()),
-    transactionId: String? = null,
+    transactionId: TransactionId? = null,
     isMine: Boolean = false,
     content: TimelineItemEventContent = aTimelineItemTextContent(),
     groupPosition: TimelineItemGroupPosition = TimelineItemGroupPosition.None,
diff --git a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/TimelineItem.kt b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/TimelineItem.kt
index 21b7e8607f..63d9379b85 100644
--- a/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/TimelineItem.kt
+++ b/features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/model/TimelineItem.kt
@@ -22,6 +22,7 @@ import io.element.android.features.messages.impl.timeline.model.event.TimelineIt
 import io.element.android.features.messages.impl.timeline.model.virtual.TimelineItemVirtualModel
 import io.element.android.libraries.designsystem.components.avatar.AvatarData
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.timeline.item.TimelineItemDebugInfo
 import io.element.android.libraries.matrix.api.timeline.item.event.InReplyTo
@@ -53,7 +54,7 @@ sealed interface TimelineItem {
     data class Event(
         val id: String,
         val eventId: EventId? = null,
-        val transactionId: String? = null,
+        val transactionId: TransactionId? = null,
         val senderId: UserId,
         val senderDisplayName: String?,
         val senderAvatar: AvatarData,
diff --git a/features/messages/impl/src/test/kotlin/io/element/android/features/messages/textcomposer/MessageComposerPresenterTest.kt b/features/messages/impl/src/test/kotlin/io/element/android/features/messages/textcomposer/MessageComposerPresenterTest.kt
index 742f994352..a2b0a1dd5a 100644
--- a/features/messages/impl/src/test/kotlin/io/element/android/features/messages/textcomposer/MessageComposerPresenterTest.kt
+++ b/features/messages/impl/src/test/kotlin/io/element/android/features/messages/textcomposer/MessageComposerPresenterTest.kt
@@ -38,6 +38,7 @@ import io.element.android.libraries.featureflag.api.FeatureFlagService
 import io.element.android.libraries.featureflag.api.FeatureFlags
 import io.element.android.libraries.featureflag.test.FakeFeatureFlagService
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.media.ImageInfo
 import io.element.android.libraries.matrix.api.media.VideoInfo
 import io.element.android.libraries.matrix.api.room.MatrixRoom
@@ -512,7 +513,7 @@ class MessageComposerPresenterTest {
 fun anEditMode(
     eventId: EventId? = AN_EVENT_ID,
     message: String = A_MESSAGE,
-    transactionId: String? = null,
+    transactionId: TransactionId? = null,
 ) = MessageComposerMode.Edit(eventId, message, transactionId)
 fun aReplyMode() = MessageComposerMode.Reply(A_USER_NAME, null, AN_EVENT_ID, A_MESSAGE)
 fun aQuoteMode() = MessageComposerMode.Quote(AN_EVENT_ID, A_MESSAGE)
diff --git a/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/core/TransactionId.kt b/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/core/TransactionId.kt
new file mode 100644
index 0000000000..0de5ccd651
--- /dev/null
+++ b/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/core/TransactionId.kt
@@ -0,0 +1,24 @@
+/*
+ * Copyright (c) 2022 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.libraries.matrix.api.core
+
+import java.io.Serializable
+
+@JvmInline
+value class TransactionId(val value: String) : Serializable {
+    override fun toString(): String = value
+}
diff --git a/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/MatrixRoom.kt b/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/MatrixRoom.kt
index 05dfda714c..6a42aa0a18 100644
--- a/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/MatrixRoom.kt
+++ b/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/room/MatrixRoom.kt
@@ -20,6 +20,7 @@ import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.ProgressCallback
 import io.element.android.libraries.matrix.api.core.RoomId
 import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.media.AudioInfo
 import io.element.android.libraries.matrix.api.media.FileInfo
@@ -70,7 +71,7 @@ interface MatrixRoom : Closeable {
 
     suspend fun sendMessage(message: String): Result<Unit>
 
-    suspend fun editMessage(originalEventId: EventId?, transactionId: String?, message: String): Result<Unit>
+    suspend fun editMessage(originalEventId: EventId?, transactionId: TransactionId?, message: String): Result<Unit>
 
     suspend fun replyMessage(eventId: EventId, message: String): Result<Unit>
 
@@ -88,9 +89,9 @@ interface MatrixRoom : Closeable {
 
     suspend fun forwardEvent(eventId: EventId, roomIds: List<RoomId>): Result<Unit>
 
-    suspend fun retrySendMessage(transactionId: String): Result<Unit>
+    suspend fun retrySendMessage(transactionId: TransactionId): Result<Unit>
 
-    suspend fun cancelSend(transactionId: String): Result<Unit>
+    suspend fun cancelSend(transactionId: TransactionId): Result<Unit>
 
     suspend fun leave(): Result<Unit>
 
diff --git a/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/MatrixTimelineItem.kt b/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/MatrixTimelineItem.kt
index e64d803aba..38974b4002 100644
--- a/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/MatrixTimelineItem.kt
+++ b/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/MatrixTimelineItem.kt
@@ -17,13 +17,14 @@
 package io.element.android.libraries.matrix.api.timeline
 
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.timeline.item.event.EventTimelineItem
 import io.element.android.libraries.matrix.api.timeline.item.virtual.VirtualTimelineItem
 
 sealed interface MatrixTimelineItem {
     data class Event(val uniqueId: Long, val event: EventTimelineItem) : MatrixTimelineItem {
         val eventId: EventId? = event.eventId
-        val transactionId: String? = event.transactionId
+        val transactionId: TransactionId? = event.transactionId
     }
 
     data class Virtual(val uniqueId: Long, val virtual: VirtualTimelineItem) : MatrixTimelineItem
diff --git a/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/EventTimelineItem.kt b/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/EventTimelineItem.kt
index 854d38b7dd..53cae7a5da 100644
--- a/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/EventTimelineItem.kt
+++ b/libraries/matrix/api/src/main/kotlin/io/element/android/libraries/matrix/api/timeline/item/event/EventTimelineItem.kt
@@ -17,12 +17,13 @@
 package io.element.android.libraries.matrix.api.timeline.item.event
 
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.timeline.item.TimelineItemDebugInfo
 
 data class EventTimelineItem(
     val eventId: EventId?,
-    val transactionId: String?,
+    val transactionId: TransactionId?,
     val isEditable: Boolean,
     val isLocal: Boolean,
     val isOwn: Boolean,
diff --git a/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/room/RustMatrixRoom.kt b/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/room/RustMatrixRoom.kt
index 11d75641c5..9eced2d5cb 100644
--- a/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/room/RustMatrixRoom.kt
+++ b/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/room/RustMatrixRoom.kt
@@ -22,6 +22,7 @@ import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.ProgressCallback
 import io.element.android.libraries.matrix.api.core.RoomId
 import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.media.AudioInfo
 import io.element.android.libraries.matrix.api.media.FileInfo
@@ -218,10 +219,10 @@ class RustMatrixRoom(
         }
     }
 
-    override suspend fun editMessage(originalEventId: EventId?, transactionId: String?, message: String): Result<Unit> = withContext(roomDispatcher) {
+    override suspend fun editMessage(originalEventId: EventId?, transactionId: TransactionId?, message: String): Result<Unit> = withContext(roomDispatcher) {
         if (originalEventId != null) {
             runCatching {
-                innerRoom.edit(/* TODO use content */ message, originalEventId.value, transactionId)
+                innerRoom.edit(/* TODO use content */ message, originalEventId.value, transactionId?.value)
             }
         } else {
             runCatching {
@@ -326,17 +327,17 @@ class RustMatrixRoom(
         }
     }
 
-    override suspend fun retrySendMessage(transactionId: String): Result<Unit> =
+    override suspend fun retrySendMessage(transactionId: TransactionId): Result<Unit> =
         withContext(roomDispatcher) {
             runCatching {
-                innerRoom.retrySend(transactionId)
+                innerRoom.retrySend(transactionId.value)
             }
         }
 
-    override suspend fun cancelSend(transactionId: String): Result<Unit> =
+    override suspend fun cancelSend(transactionId: TransactionId): Result<Unit> =
         withContext(roomDispatcher) {
             runCatching {
-                innerRoom.cancelSend(transactionId)
+                innerRoom.cancelSend(transactionId.value)
             }
         }
 
diff --git a/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/item/event/EventTimelineItemMapper.kt b/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/item/event/EventTimelineItemMapper.kt
index b4887faf68..380acabacd 100644
--- a/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/item/event/EventTimelineItemMapper.kt
+++ b/libraries/matrix/impl/src/main/kotlin/io/element/android/libraries/matrix/impl/timeline/item/event/EventTimelineItemMapper.kt
@@ -17,6 +17,7 @@
 package io.element.android.libraries.matrix.impl.timeline.item.event
 
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.timeline.item.TimelineItemDebugInfo
 import io.element.android.libraries.matrix.api.timeline.item.event.EventReaction
@@ -34,7 +35,7 @@ class EventTimelineItemMapper(private val contentMapper: TimelineEventContentMap
     fun map(eventTimelineItem: RustEventTimelineItem): EventTimelineItem = eventTimelineItem.use {
         EventTimelineItem(
             eventId = it.eventId()?.let(::EventId),
-            transactionId = it.transactionId(),
+            transactionId = it.transactionId()?.let(::TransactionId),
             isEditable = it.isEditable(),
             isLocal = it.isLocal(),
             isOwn = it.isOwn(),
diff --git a/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/TestData.kt b/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/TestData.kt
index 0227763479..3da47a8563 100644
--- a/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/TestData.kt
+++ b/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/TestData.kt
@@ -22,6 +22,7 @@ import io.element.android.libraries.matrix.api.core.RoomId
 import io.element.android.libraries.matrix.api.core.SessionId
 import io.element.android.libraries.matrix.api.core.SpaceId
 import io.element.android.libraries.matrix.api.core.ThreadId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
 import java.util.UUID
 
@@ -38,7 +39,7 @@ val A_ROOM_ID_2 = RoomId("!aRoomId2:domain")
 val A_THREAD_ID = ThreadId("\$aThreadId")
 val AN_EVENT_ID = EventId("\$anEventId")
 val AN_EVENT_ID_2 = EventId("\$anEventId2")
-const val A_TRANSACTION_ID = "aTransactionId"
+val A_TRANSACTION_ID = TransactionId("aTransactionId")
 const val A_UNIQUE_ID = "aUniqueId"
 
 const val A_ROOM_NAME = "A room name"
diff --git a/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/FakeMatrixRoom.kt b/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/FakeMatrixRoom.kt
index 3f265f392a..176d9109da 100644
--- a/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/FakeMatrixRoom.kt
+++ b/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/FakeMatrixRoom.kt
@@ -20,6 +20,7 @@ import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.ProgressCallback
 import io.element.android.libraries.matrix.api.core.RoomId
 import io.element.android.libraries.matrix.api.core.SessionId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.room.location.AssetType
 import io.element.android.libraries.matrix.api.media.AudioInfo
@@ -164,17 +165,17 @@ class FakeMatrixRoom(
         return toggleReactionResult
     }
 
-    override suspend fun retrySendMessage(transactionId: String): Result<Unit> {
+    override suspend fun retrySendMessage(transactionId: TransactionId): Result<Unit> {
         retrySendMessageCount++
         return retrySendMessageResult
     }
 
-    override suspend fun cancelSend(transactionId: String): Result<Unit> {
+    override suspend fun cancelSend(transactionId: TransactionId): Result<Unit> {
         cancelSendCount++
         return cancelSendResult
     }
 
-    override suspend fun editMessage(originalEventId: EventId?, transactionId: String?, message: String): Result<Unit> {
+    override suspend fun editMessage(originalEventId: EventId?, transactionId: TransactionId?, message: String): Result<Unit> {
         editMessageCalls += message
         return Result.success(Unit)
     }
diff --git a/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/RoomSummaryFixture.kt b/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/RoomSummaryFixture.kt
index 0a956577ca..0154067df5 100644
--- a/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/RoomSummaryFixture.kt
+++ b/libraries/matrix/test/src/main/kotlin/io/element/android/libraries/matrix/test/room/RoomSummaryFixture.kt
@@ -18,6 +18,7 @@ package io.element.android.libraries.matrix.test.room
 
 import io.element.android.libraries.matrix.api.core.EventId
 import io.element.android.libraries.matrix.api.core.RoomId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.core.UserId
 import io.element.android.libraries.matrix.api.room.RoomSummary
 import io.element.android.libraries.matrix.api.room.RoomSummaryDetails
@@ -88,7 +89,7 @@ fun aRoomMessage(
 
 fun anEventTimelineItem(
     eventId: EventId = AN_EVENT_ID,
-    transactionId: String? = null,
+    transactionId: TransactionId? = null,
     isEditable: Boolean = false,
     isLocal: Boolean = false,
     isOwn: Boolean = false,
diff --git a/libraries/textcomposer/src/main/kotlin/io/element/android/libraries/textcomposer/MessageComposerMode.kt b/libraries/textcomposer/src/main/kotlin/io/element/android/libraries/textcomposer/MessageComposerMode.kt
index 1a9f20a060..128d754fa2 100644
--- a/libraries/textcomposer/src/main/kotlin/io/element/android/libraries/textcomposer/MessageComposerMode.kt
+++ b/libraries/textcomposer/src/main/kotlin/io/element/android/libraries/textcomposer/MessageComposerMode.kt
@@ -18,6 +18,7 @@ package io.element.android.libraries.textcomposer
 
 import android.os.Parcelable
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.ui.components.AttachmentThumbnailInfo
 import kotlinx.parcelize.Parcelize
 
@@ -29,7 +30,7 @@ sealed interface MessageComposerMode : Parcelable {
         MessageComposerMode
 
     @Parcelize
-    data class Edit(override val eventId: EventId?, override val defaultContent: CharSequence, val transactionId: String?) :
+    data class Edit(override val eventId: EventId?, override val defaultContent: CharSequence, val transactionId: TransactionId?) :
         Special(eventId, defaultContent)
 
     @Parcelize
diff --git a/libraries/textcomposer/src/main/kotlin/io/element/android/libraries/textcomposer/TextComposer.kt b/libraries/textcomposer/src/main/kotlin/io/element/android/libraries/textcomposer/TextComposer.kt
index b757f69f03..5c82ff3fdd 100644
--- a/libraries/textcomposer/src/main/kotlin/io/element/android/libraries/textcomposer/TextComposer.kt
+++ b/libraries/textcomposer/src/main/kotlin/io/element/android/libraries/textcomposer/TextComposer.kt
@@ -77,6 +77,7 @@ import io.element.android.libraries.designsystem.theme.components.Icon
 import io.element.android.libraries.designsystem.theme.components.Surface
 import io.element.android.libraries.designsystem.theme.components.Text
 import io.element.android.libraries.matrix.api.core.EventId
+import io.element.android.libraries.matrix.api.core.TransactionId
 import io.element.android.libraries.matrix.api.media.MediaSource
 import io.element.android.libraries.matrix.ui.components.AttachmentThumbnail
 import io.element.android.libraries.matrix.ui.components.AttachmentThumbnailInfo
@@ -449,7 +450,7 @@ fun TextComposerEditPreview() = ElementPreview {
     TextComposer(
         onSendMessage = {},
         onComposerTextChange = {},
-        composerMode = MessageComposerMode.Edit(EventId("$1234"), "Some text", "1234"),
+        composerMode = MessageComposerMode.Edit(EventId("$1234"), "Some text", TransactionId("1234")),
         onResetComposerMode = {},
         composerCanSendMessage = true,
         composerText = "A message",