diff --git a/CHANGELOG.md b/CHANGELOG.md
index e2b21ad6..fedd5e94 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -17,13 +17,13 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
   where the fee payer is the loaded user
 - Add `extraData` to `TransferDetails`, it contains the raw `extraData` that was present in the transfer
   for which details are returned
-- Add `paymentRequestId` and `messageId` to `TransferDetails` corresponding to the decoded `extraData`
-- Add option to `Payment.preparePayment` function `options.addMessageId: boolean = true` that signals whether
-  a messageId should be generated and added to the payment's extraData.
-- Add `messageId` to the returned values of `Payment.preparePayment`
+- Add `paymentRequestId` and `transferId` to `TransferDetails` corresponding to the decoded `extraData`
+- Add option to `Payment.preparePayment` function `options.addTransferId: boolean = true` that signals whether
+  a `transferId` should be generated and added to the payment's extraData.
+- Add `transferId` to the returned values of `Payment.preparePayment`
 - Add function `Payment.confirmPayment` to confirm any `PaymentTxObject` returned by `prepare`
   and potentially send a payment message along with the payment
-- Add function `Messaging.paymentMessage` to send a payment message for a messageId to a counterparty address
+- Add function `Messaging.paymentMessage` to send a payment message for a `transferId` to a counterparty address
 
 ### Deprecated
 
diff --git a/src/Messaging.ts b/src/Messaging.ts
index 19601d49..060b4f6b 100644
--- a/src/Messaging.ts
+++ b/src/Messaging.ts
@@ -110,18 +110,18 @@ export class Messaging {
   /**
    * Sends a payment message to given `counterParty` and returns created message.
    * @param counterPartyAddress Address of counter party.
-   * @param messageId Message id of the payment
+   * @param transferId Transfer ID of the payment
    * @param subject Subject that will be sent to the counterparty
    */
   public async paymentMessage(
     counterPartyAddress: string,
-    messageId: string,
+    transferId: string,
     subject: string
   ): Promise<PaymentMessage> {
     const type = 'PaymentMessage'
     const message = {
       type,
-      messageId,
+      transferId,
       subject
     }
     await this.sendMessage(counterPartyAddress, type, message)
diff --git a/src/Payment.ts b/src/Payment.ts
index 27af4a52..383ffde1 100644
--- a/src/Payment.ts
+++ b/src/Payment.ts
@@ -101,13 +101,13 @@ export class Payment {
    * @param options.feePayer Either `sender` or `receiver`. Specifies who pays network fees.
    * @param options.extraData Extra data that will appear in the Transfer event when successful.
    * @param options.paymentRequestId Payment request identifier that gets encoded to the extra data.
-   * @param options.addMessageId Whether a message id should be added to the payment, default to true.
+   * @param options.addTransferId Whether a transfer id should be added to the payment, default to true.
    */
   public async prepare(
     networkAddress: string,
     receiverAddress: string,
     value: number | string,
-    options: PaymentOptions = { addMessageId: true }
+    options: PaymentOptions = { addTransferId: true }
   ): Promise<PaymentTxObject> {
     const {
       gasPrice,
@@ -115,20 +115,20 @@ export class Payment {
       networkDecimals,
       extraData,
       paymentRequestId,
-      addMessageId
+      addTransferId
     } = options
     const decimals = await this.currencyNetwork.getDecimals(networkAddress, {
       networkDecimals
     })
-    let messageId: string
-    if (addMessageId) {
+    let transferId: string
+    if (addTransferId) {
       // 19 decimals fit in 64 bits
-      messageId = utils.convertToHexString(utils.generateRandomNumber(19))
+      transferId = utils.convertToHexString(utils.generateRandomNumber(19))
     }
     const encodedExtraData: string = encode({
       extraData,
       paymentRequestId,
-      messageId
+      transferId
     })
 
     const { path, maxFees, feePayer } = await this.getTransferPathInfo(
@@ -174,7 +174,7 @@ export class Payment {
         path,
         receiverAddress,
         rawTx,
-        messageId: messageId || null
+        transferId: transferId || null
       }
     } else {
       throw new Error('Could not find a path with enough capacity.')
@@ -293,28 +293,28 @@ export class Payment {
 
   /**
    * Signs the rawTx provided as returned by `prepare`
-   * and sends the signed transaction as well as the message with messageId
+   * and sends the signed transaction as well as the message with transferId
    * Can be directly given a `PaymentTxObject` object as returned by `prepare`
    * @param rawTx Raw transaction object.
    * @param receiverAddress Address of the receiver of the message for the payment.
-   * @param messageId The messageId returned when preparing a payment with message.
+   * @param transferId The transfer id returned when preparing a payment with message.
    * @param message The message to be sent.
    */
   public async confirmPayment(
     {
       rawTx,
       receiverAddress,
-      messageId
-    }: { rawTx: RawTxObject; receiverAddress: string; messageId?: string },
+      transferId
+    }: { rawTx: RawTxObject; receiverAddress: string; transferId?: string },
     message?: string
   ) {
     if (message) {
-      if (!messageId) {
+      if (!transferId) {
         throw new Error(
-          'Cannot use `message` if payment was prepared without `messageId`.'
+          'Cannot use `message` if payment was prepared without `transferId`.'
         )
       }
-      await this.messaging.paymentMessage(receiverAddress, messageId, message)
+      await this.messaging.paymentMessage(receiverAddress, transferId, message)
     }
     return this.transaction.confirm(rawTx)
   }
@@ -513,21 +513,21 @@ export class Payment {
 function encode({
   extraData,
   paymentRequestId,
-  messageId
+  transferId
 }: {
   extraData: string
   paymentRequestId: string
-  messageId?: string
+  transferId?: string
 }) {
-  if (extraData && (paymentRequestId || messageId)) {
+  if (extraData && (paymentRequestId || transferId)) {
     throw Error(
-      'Can not encode extraData and paymentRequestId or messageId at the same time currently'
+      'Can not encode extraData and paymentRequestId or transferId at the same time currently'
     )
   }
   if (extraData) {
     return extraData
-  } else if (paymentRequestId || messageId) {
-    return encodeExtraData({ paymentRequestId, messageId })
+  } else if (paymentRequestId || transferId) {
+    return encodeExtraData({ paymentRequestId, transferId })
   } else {
     return '0x'
   }
diff --git a/src/extraData.ts b/src/extraData.ts
index bf7a26a2..5b521ada 100644
--- a/src/extraData.ts
+++ b/src/extraData.ts
@@ -4,25 +4,25 @@ export const MSG_PACK_ID = '0x544c4d50' // hex encoded "TLMP" (Trustlines Messag
 
 export interface ExtraData {
   paymentRequestId?: string
-  messageId?: string
+  transferId?: string
 }
 
 interface ExtraDataEncoding {
   prId?: ArrayBufferView
-  mgId?: ArrayBufferView
+  trId?: ArrayBufferView
 }
 
 export function encode(extraData: ExtraData): string {
-  const { paymentRequestId, messageId } = extraData
-  if (!paymentRequestId && !messageId) {
+  const { paymentRequestId, transferId } = extraData
+  if (!paymentRequestId && !transferId) {
     return '0x'
   } else {
     const data: ExtraDataEncoding = {}
     if (paymentRequestId) {
       data.prId = hexToArray(paymentRequestId)
     }
-    if (messageId) {
-      data.mgId = hexToArray(messageId)
+    if (transferId) {
+      data.trId = hexToArray(transferId)
     }
     const enc = msgPack.encode(data)
     return MSG_PACK_ID + remove0xPrefix(arrayToHex(enc))
@@ -52,7 +52,7 @@ export function decode(encodedExtraData: string): ExtraData {
 
   return {
     paymentRequestId: arrayToHex(extraData.prId),
-    messageId: arrayToHex(extraData.mgId)
+    transferId: arrayToHex(extraData.trId)
   }
 }
 
@@ -85,8 +85,8 @@ export function processExtraData(object) {
     object.paymentRequestId = decodedExtraData
       ? decodedExtraData.paymentRequestId || null
       : null
-    object.messageId = decodedExtraData
-      ? decodedExtraData.messageId || null
+    object.transferId = decodedExtraData
+      ? decodedExtraData.transferId || null
       : null
   }
   return object
diff --git a/src/typings.ts b/src/typings.ts
index 8c96b5bd..d2b0ab4b 100644
--- a/src/typings.ts
+++ b/src/typings.ts
@@ -79,7 +79,7 @@ export interface PaymentOptions extends TLOptions {
   feePayer?: FeePayer
   extraData?: string
   paymentRequestId?: string
-  addMessageId?: boolean
+  addTransferId?: boolean
 }
 
 export interface TrustlineUpdateOptions extends TLOptions {
@@ -137,7 +137,7 @@ export interface NetworkTransferEvent extends NetworkEvent {
   amount: Amount
   extraData: string
   paymentRequestId: string
-  messageId: string
+  transferId: string
 }
 
 export interface NetworkTrustlineUpdateEventRaw extends NetworkEvent {
@@ -226,7 +226,7 @@ export interface PaymentRequestDeclineMessage {
 
 export interface PaymentMessage {
   type: string
-  messageId: string
+  transferId: string
   subject: string
 }
 
@@ -436,7 +436,7 @@ export interface PaymentTxObject extends TxObject {
   receiverAddress: string
   feePayer: FeePayer
   maxFees: Amount
-  messageId?: string
+  transferId?: string
 }
 
 export enum FeePayer {
@@ -697,7 +697,7 @@ export interface TransferDetails {
   feesPaid: Amount[]
   extraData: string
   paymentRequestId: string
-  messageId: string
+  transferId: string
 }
 
 export interface TransferIdentifier {
diff --git a/tests/e2e/Event.test.ts b/tests/e2e/Event.test.ts
index ee09c13c..fe543cb5 100644
--- a/tests/e2e/Event.test.ts
+++ b/tests/e2e/Event.test.ts
@@ -73,7 +73,7 @@ describe('e2e', () => {
           1.5,
           {
             extraData,
-            addMessageId: false
+            addTransferId: false
           }
         )
         await tl1.payment.confirm(rawTx)
@@ -98,7 +98,7 @@ describe('e2e', () => {
         expect(last.amount).to.have.keys('raw', 'value', 'decimals')
         expect(last.amount.value).to.eq('1.5')
         expect(last.extraData).to.eq(extraData)
-        expect(last.messageId).to.be.a('null')
+        expect(last.transferId).to.be.a('null')
         expect(last.paymentRequestId).to.be.a('null')
         expect(last.logIndex).to.be.a('number')
         expect(last.blockHash).to.be.a('string')
@@ -110,7 +110,7 @@ describe('e2e', () => {
       let acceptTxHash
       let cancelUpdateTxHash
       let tlTransferTxHash
-      let tlTransferMessageId
+      let tlTransferTransferId
       let depositTxHash
       let withdrawTxHash
       let transferTxHash
@@ -164,7 +164,7 @@ describe('e2e', () => {
           1,
           { paymentRequestId }
         )
-        tlTransferMessageId = tlTransferTx.messageId
+        tlTransferTransferId = tlTransferTx.transferId
         tlTransferTxHash = await tl1.payment.confirm(tlTransferTx.rawTx)
         await wait()
 
@@ -338,8 +338,8 @@ describe('e2e', () => {
           (tlTransferEvents[0] as NetworkTransferEvent).paymentRequestId
         ).to.equal(paymentRequestId)
         expect(
-          (tlTransferEvents[0] as NetworkTransferEvent).messageId
-        ).to.equal(tlTransferMessageId)
+          (tlTransferEvents[0] as NetworkTransferEvent).transferId
+        ).to.equal(tlTransferTransferId)
 
         // events thrown on deposit
         const depositEvents = allEvents.filter(
@@ -564,7 +564,7 @@ describe('e2e', () => {
           'paymentRequestId',
           paymentRequestId
         )
-        expect(transferEvent).to.have.property('messageId')
+        expect(transferEvent).to.have.property('transferId')
         expect(transferEvent.blockHash).to.be.a('string')
         expect(transferEvent.logIndex).be.a('number')
 
diff --git a/tests/e2e/Messaging.test.ts b/tests/e2e/Messaging.test.ts
index 3acad261..f600cefb 100644
--- a/tests/e2e/Messaging.test.ts
+++ b/tests/e2e/Messaging.test.ts
@@ -99,7 +99,7 @@ describe('e2e', () => {
             'test message'
           )
           expect(sentPaymentMessage.type).to.equal('PaymentMessage')
-          expect(sentPaymentMessage.messageId).to.equal('0x10')
+          expect(sentPaymentMessage.transferId).to.equal('0x10')
           expect(sentPaymentMessage.subject).to.equal('test message')
         })
       })
@@ -177,7 +177,7 @@ describe('e2e', () => {
         it('should receive payment message', async () => {
           expect(messages[4]).to.have.property('type', 'PaymentMessage')
           expect(messages[4].timestamp).to.be.a('number')
-          expect(messages[4].messageId).to.be.a('string')
+          expect(messages[4].transferId).to.be.a('string')
           expect(messages[4]).to.have.property('subject', 'payment message')
         })
 
diff --git a/tests/e2e/Payment.test.ts b/tests/e2e/Payment.test.ts
index 7ffcef5f..4ae58204 100644
--- a/tests/e2e/Payment.test.ts
+++ b/tests/e2e/Payment.test.ts
@@ -125,7 +125,7 @@ describe('e2e', () => {
           const options = {
             feePayer: FeePayer.Sender,
             extraData,
-            addMessageId: false
+            addTransferId: false
           }
           const pathObj = await tl1.payment.getTransferPathInfo(
             network.address,
@@ -154,7 +154,7 @@ describe('e2e', () => {
             'maxFees',
             'path',
             'receiverAddress',
-            'messageId'
+            'transferId'
           )
           expect(preparedPayment.feePayer).to.equal(FeePayer.Sender)
         })
@@ -166,7 +166,7 @@ describe('e2e', () => {
             2.25,
             {
               extraData,
-              addMessageId: false
+              addTransferId: false
             }
           )
           expect(preparedPayment).to.have.all.keys(
@@ -176,7 +176,7 @@ describe('e2e', () => {
             'maxFees',
             'path',
             'receiverAddress',
-            'messageId'
+            'transferId'
           )
           expect(preparedPayment.feePayer).to.equal(FeePayer.Sender)
         })
@@ -197,7 +197,7 @@ describe('e2e', () => {
             'maxFees',
             'path',
             'receiverAddress',
-            'messageId'
+            'transferId'
           )
           expect(preparedPayment.feePayer).to.equal(FeePayer.Receiver)
         })
@@ -219,7 +219,7 @@ describe('e2e', () => {
             'maxFees',
             'path',
             'receiverAddress',
-            'messageId'
+            'transferId'
           )
           expect(preparedPayment.feePayer).to.equal(FeePayer.Sender)
         })
@@ -324,7 +324,7 @@ describe('e2e', () => {
             1,
             {
               extraData,
-              addMessageId: false
+              addTransferId: false
             }
           )
           const txHash = await tl1.payment.confirm(rawTx)
@@ -348,7 +348,7 @@ describe('e2e', () => {
         describe('confirm with message', () => {
           const messages = []
           let stream
-          let messageId: string
+          let transferId: string
           const paymentMessage = 'test message'
 
           before(async () => {
@@ -365,7 +365,7 @@ describe('e2e', () => {
               user2.address,
               1
             )
-            messageId = preparedPayment.messageId
+            transferId = preparedPayment.transferId
             const txHash = await tl1.payment.confirmPayment(
               preparedPayment,
               paymentMessage
@@ -378,7 +378,7 @@ describe('e2e', () => {
             // We expect to have messages for `WebsocketOpen` and then the payment message
             expect(messages).to.have.lengthOf(2)
             expect(messages[1]).to.have.property('type', 'PaymentMessage')
-            expect(messages[1]).to.have.property('messageId', messageId)
+            expect(messages[1]).to.have.property('transferId', transferId)
             expect(messages[1]).to.have.property('subject', paymentMessage)
           })
 
@@ -389,7 +389,7 @@ describe('e2e', () => {
       })
 
       describe('#get()', () => {
-        let messageId: string
+        let transferId: string
 
         before(async () => {
           const preparedPayment = await tl1.payment.prepare(
@@ -398,10 +398,10 @@ describe('e2e', () => {
             1.5,
             {
               paymentRequestId,
-              addMessageId: true
+              addTransferId: true
             }
           )
-          messageId = preparedPayment.messageId
+          transferId = preparedPayment.transferId
           await tl1.payment.confirm(preparedPayment.rawTx)
           await wait()
         })
@@ -421,7 +421,7 @@ describe('e2e', () => {
           expect(latestTransfer.amount.value).to.equal('1.5')
           expect(latestTransfer.extraData).to.be.a('string')
           expect(latestTransfer.paymentRequestId).to.equal(paymentRequestId)
-          expect(latestTransfer.messageId).to.equal(messageId)
+          expect(latestTransfer.transferId).to.equal(transferId)
           expect(latestTransfer.blockNumber).to.be.a('number')
           expect(latestTransfer.direction).to.equal('sent')
           expect(latestTransfer.networkAddress).to.be.a('string')
@@ -441,7 +441,7 @@ describe('e2e', () => {
             user3.address,
             transferValue,
             {
-              addMessageId: true,
+              addTransferId: true,
               paymentRequestId
             }
           )
@@ -463,7 +463,7 @@ describe('e2e', () => {
             'feesPaid',
             'extraData',
             'paymentRequestId',
-            'messageId'
+            'transferId'
           )
           expect(transferDetails.path).to.be.an('Array')
           expect(transferDetails.path).to.deep.equal([
@@ -492,7 +492,7 @@ describe('e2e', () => {
           )
           expect(transferDetails.extraData).to.be.a('string')
           expect(transferDetails.paymentRequestId).to.equal(paymentRequestId)
-          expect(transferDetails.messageId).to.equal(transfer.messageId)
+          expect(transferDetails.transferId).to.equal(transfer.transferId)
         })
 
         it('should return details for transfer via id', async () => {
@@ -504,7 +504,7 @@ describe('e2e', () => {
             transferValue,
             {
               extraData,
-              addMessageId: false
+              addTransferId: false
             }
           )
           await tl1.payment.confirm(transfer.rawTx)
@@ -527,7 +527,7 @@ describe('e2e', () => {
             'feesPaid',
             'extraData',
             'paymentRequestId',
-            'messageId'
+            'transferId'
           )
           expect(transferDetails.path).to.be.an('Array')
           expect(transferDetails.path).to.deep.equal([
@@ -556,7 +556,7 @@ describe('e2e', () => {
           )
           expect(transferDetails.extraData).to.equal('0x12ab34ef')
           expect(transferDetails.paymentRequestId).to.be.a('null')
-          expect(transferDetails.messageId).to.be.a('null')
+          expect(transferDetails.transferId).to.be.a('null')
         })
       })
 
diff --git a/tests/unit/extraData.test.ts b/tests/unit/extraData.test.ts
index 402a45b6..fed27b39 100644
--- a/tests/unit/extraData.test.ts
+++ b/tests/unit/extraData.test.ts
@@ -11,17 +11,17 @@ describe('unit', () => {
       )
     })
 
-    it('should encode and decode messageId correctly', () => {
-      const extraData = { messageId: '0x1234567890abcdef' }
-      expect(extraData.messageId).to.be.deep.eq(
-        decode(encode(extraData)).messageId
+    it('should encode and decode transferId correctly', () => {
+      const extraData = { transferId: '0x1234567890abcdef' }
+      expect(extraData.transferId).to.be.deep.eq(
+        decode(encode(extraData)).transferId
       )
     })
 
     it('should encode and decode combined extra data correctly', () => {
       const extraData = {
         paymentRequestId: '0x1212343456567878',
-        messageId: '0x1234567890abcdef'
+        transferId: '0x1234567890abcdef'
       }
       expect(extraData).to.be.deep.eq(decode(encode(extraData)))
     })