diff --git a/src/api/buildPayTransaction.test.ts b/src/api/buildPayTransaction.test.ts
new file mode 100644
index 0000000000..60e0b14863
--- /dev/null
+++ b/src/api/buildPayTransaction.test.ts
@@ -0,0 +1,131 @@
+import { base, mainnet } from 'viem/chains';
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import type { Mock } from 'vitest';
+import { PAY_HYDRATE_CHARGE } from '../network/definitions/pay';
+import { sendRequest } from '../network/request';
+import {
+  PAY_INVALID_CHARGE_ERROR_MESSAGE,
+  PAY_UNSUPPORTED_CHAIN_ERROR_MESSAGE,
+  UNCAUGHT_PAY_ERROR_MESSAGE,
+} from '../pay/constants';
+/**
+ * @vitest-environment node
+ */
+import { buildPayTransaction } from './buildPayTransaction';
+import {
+  MOCK_HYDRATE_CHARGE_INVALID_CHARGE_ERROR_RESPONSE,
+  MOCK_HYDRATE_CHARGE_SUCCESS_RESPONSE,
+  MOCK_INVALID_CHARGE_ID,
+  MOCK_VALID_CHARGE_ID,
+  MOCK_VALID_PAYER_ADDRESS,
+} from './mocks';
+import type {
+  BuildPayTransactionParams,
+  HydrateChargeAPIParams,
+} from './types';
+
+vi.mock('../network/request');
+
+describe('buildPayTransaction', () => {
+  afterEach(() => {
+    vi.clearAllMocks();
+  });
+
+  it('should return a Pay Transaction', async () => {
+    const mockParams: BuildPayTransactionParams = {
+      address: MOCK_VALID_PAYER_ADDRESS,
+      chainId: base.id,
+      chargeId: MOCK_VALID_CHARGE_ID,
+    };
+    const mockAPIParams: HydrateChargeAPIParams = {
+      sender: MOCK_VALID_PAYER_ADDRESS,
+      chargeId: MOCK_VALID_CHARGE_ID,
+      chainId: base.id,
+    };
+    (sendRequest as Mock).mockResolvedValue(
+      MOCK_HYDRATE_CHARGE_SUCCESS_RESPONSE,
+    );
+    const payTransaction = await buildPayTransaction(mockParams);
+    expect(payTransaction).toEqual(MOCK_HYDRATE_CHARGE_SUCCESS_RESPONSE.result);
+    expect(sendRequest).toHaveBeenCalledTimes(1);
+    expect(sendRequest).toHaveBeenCalledWith(PAY_HYDRATE_CHARGE, [
+      mockAPIParams,
+    ]);
+  });
+
+  it('should return an error for chains other than Base', async () => {
+    const mockParams: BuildPayTransactionParams = {
+      address: MOCK_VALID_PAYER_ADDRESS,
+      chainId: mainnet.id,
+      chargeId: MOCK_VALID_CHARGE_ID,
+    };
+    (sendRequest as Mock).mockResolvedValue(
+      MOCK_HYDRATE_CHARGE_SUCCESS_RESPONSE,
+    );
+    const error = await buildPayTransaction(mockParams);
+    expect(error).toEqual({
+      code: 'AmBPTa01',
+      error: 'Pay Transactions must be on Base',
+      message: PAY_UNSUPPORTED_CHAIN_ERROR_MESSAGE,
+    });
+    expect(sendRequest).not.toHaveBeenCalled();
+  });
+
+  it('should return an error if sendRequest fails', async () => {
+    const mockParams: BuildPayTransactionParams = {
+      address: MOCK_VALID_PAYER_ADDRESS,
+      chainId: base.id,
+      chargeId: MOCK_VALID_CHARGE_ID,
+    };
+    const mockAPIParams: HydrateChargeAPIParams = {
+      sender: MOCK_VALID_PAYER_ADDRESS,
+      chargeId: MOCK_VALID_CHARGE_ID,
+      chainId: base.id,
+    };
+    (sendRequest as Mock).mockResolvedValue(
+      MOCK_HYDRATE_CHARGE_SUCCESS_RESPONSE,
+    );
+    const hydratedCharge = await buildPayTransaction(mockParams);
+    expect(hydratedCharge).toEqual(MOCK_HYDRATE_CHARGE_SUCCESS_RESPONSE.result);
+    expect(sendRequest).toHaveBeenCalledTimes(1);
+    expect(sendRequest).toHaveBeenCalledWith(PAY_HYDRATE_CHARGE, [
+      mockAPIParams,
+    ]);
+    const mockError = new Error(
+      'buildPayTransaction: Error: Failed to send request',
+    );
+    (sendRequest as Mock).mockRejectedValue(mockError);
+    const error = await buildPayTransaction(mockParams);
+    expect(error).toEqual({
+      code: 'AmBPTa03',
+      error: 'Something went wrong',
+      message: UNCAUGHT_PAY_ERROR_MESSAGE,
+    });
+  });
+
+  it('should return an error object from buildPayTransaction', async () => {
+    const mockParams: BuildPayTransactionParams = {
+      address: MOCK_VALID_PAYER_ADDRESS,
+      chainId: base.id,
+      chargeId: MOCK_INVALID_CHARGE_ID,
+    };
+    const mockAPIParams: HydrateChargeAPIParams = {
+      sender: MOCK_VALID_PAYER_ADDRESS,
+      chargeId: MOCK_INVALID_CHARGE_ID,
+      chainId: base.id,
+    };
+    (sendRequest as Mock).mockResolvedValue(
+      MOCK_HYDRATE_CHARGE_INVALID_CHARGE_ERROR_RESPONSE,
+    );
+    const error = await buildPayTransaction(mockParams);
+    expect(error).toEqual({
+      code: 'AmBPTa02',
+      error: 'method not found - Not found',
+      message: PAY_INVALID_CHARGE_ERROR_MESSAGE,
+    });
+    expect(sendRequest).toHaveBeenCalledTimes(1);
+    expect(sendRequest).toHaveBeenCalledWith(PAY_HYDRATE_CHARGE, [
+      mockAPIParams,
+    ]);
+  });
+});
diff --git a/src/api/buildPayTransaction.ts b/src/api/buildPayTransaction.ts
new file mode 100644
index 0000000000..8febe87f7b
--- /dev/null
+++ b/src/api/buildPayTransaction.ts
@@ -0,0 +1,50 @@
+import { base } from 'viem/chains';
+import { PAY_HYDRATE_CHARGE } from '../network/definitions/pay';
+import { sendRequest } from '../network/request';
+import { PAY_UNSUPPORTED_CHAIN_ERROR_MESSAGE } from '../pay/constants';
+import type {
+  BuildPayTransactionParams,
+  BuildPayTransactionResponse,
+  HydrateChargeAPIParams,
+} from './types';
+import { getPayErrorMessage } from './utils/getPayErrorMessage';
+
+export async function buildPayTransaction({
+  address,
+  chainId,
+  chargeId,
+}: BuildPayTransactionParams): Promise<BuildPayTransactionResponse> {
+  if (chainId !== base.id) {
+    return {
+      code: 'AmBPTa01', // Api Module Build Pay Transaction Error 01
+      error: 'Pay Transactions must be on Base',
+      message: PAY_UNSUPPORTED_CHAIN_ERROR_MESSAGE,
+    };
+  }
+  try {
+    const res = await sendRequest<
+      HydrateChargeAPIParams,
+      BuildPayTransactionResponse
+    >(PAY_HYDRATE_CHARGE, [
+      {
+        sender: address,
+        chainId: chainId,
+        chargeId,
+      },
+    ]);
+    if (res.error) {
+      return {
+        code: 'AmBPTa02', // Api Module Build Pay Transaction Error 02
+        error: res.error.message,
+        message: getPayErrorMessage(res.error?.code),
+      };
+    }
+    return res.result;
+  } catch (_error) {
+    return {
+      code: 'AmBPTa03', // Api Module Build Pay Transaction Error 03
+      error: 'Something went wrong',
+      message: getPayErrorMessage(),
+    };
+  }
+}
diff --git a/src/api/index.ts b/src/api/index.ts
index b532852214..0f88f9e12d 100644
--- a/src/api/index.ts
+++ b/src/api/index.ts
@@ -1,9 +1,12 @@
 // 🌲☀️🌲
 export { buildSwapTransaction } from './buildSwapTransaction';
+export { buildPayTransaction } from './buildPayTransaction';
 export { getSwapQuote } from './getSwapQuote';
 export { getTokens } from './getTokens';
 export type {
   APIError,
+  BuildPayTransactionParams,
+  BuildPayTransactionResponse,
   BuildSwapTransactionParams,
   GetSwapQuoteParams,
   GetSwapQuoteResponse,
diff --git a/src/api/mocks.ts b/src/api/mocks.ts
new file mode 100644
index 0000000000..7457c43cad
--- /dev/null
+++ b/src/api/mocks.ts
@@ -0,0 +1,38 @@
+export const MOCK_VALID_CHARGE_ID = '1b03e80d-4e87-46fd-9772-422a1b693fb7';
+export const MOCK_INVALID_CHARGE_ID = '00000000-0000-0000-0000-000000000000';
+export const MOCK_VALID_PAYER_ADDRESS =
+  '0x98fAbEA34A3A377916EBF7793f37E11EE98D29Eb';
+export const MOCK_HYDRATE_CHARGE_SUCCESS_RESPONSE = {
+  id: 1,
+  jsonrpc: '2.0',
+  result: {
+    id: MOCK_VALID_CHARGE_ID,
+    callData: {
+      deadline: '2024-08-29T23:00:38Z',
+      feeAmount: '10000',
+      id: '0xd2e57fb373f246768a193cadd4a5ce1e',
+      operator: '0xd1db362f9d23a029834375afa2b37d91d2e67a95',
+      prefix: '0x4b3220496e666f726d6174696f6e616c204d6573736167653a20333220',
+      recipient: '0xb724dcF5f1156dd8E2AB217921b5Bd46a9e5cAa5',
+      recipientAmount: '990000',
+      recipientCurrency: '0xF175520C52418dfE19C8098071a252da48Cd1C19',
+      refundDestination: MOCK_VALID_PAYER_ADDRESS,
+      signature:
+        '0xb49a08026bdfdc55e3b1b797a9481fbdb7a9246c73f5f77fece76d5f24e979561f2168862aed0dd72980a4f9930cf23836084f3326b98b5546b280c4f0d57aae1b',
+    },
+    metaData: {
+      chainId: 8453,
+      contractAddress: '0x131642c019AF815Ae5F9926272A70C84AE5C37ab',
+      sender: MOCK_VALID_PAYER_ADDRESS,
+      settlementCurrencyAddress: '0xF175520C52418dfE19C8098071a252da48Cd1C19',
+    },
+  },
+};
+export const MOCK_HYDRATE_CHARGE_INVALID_CHARGE_ERROR_RESPONSE = {
+  id: 1,
+  jsonrpc: '2.0',
+  error: {
+    code: -32601,
+    message: 'method not found - Not found',
+  },
+};
diff --git a/src/api/types.ts b/src/api/types.ts
index 121224540a..14a5adf245 100644
--- a/src/api/types.ts
+++ b/src/api/types.ts
@@ -79,3 +79,47 @@ export type RawTransactionData = {
 };
 
 export type SwapAPIParams = GetQuoteAPIParams | GetSwapAPIParams;
+
+/**
+ * Note: exported as public Type
+ */
+export type BuildPayTransactionParams = {
+  address: Address; // The address of the wallet paying
+  chainId: number; // The Chain ID of the payment Network (only Base is supported)
+  chargeId: string; // The ID of the Commerce Charge to be paid
+};
+
+export type HydrateChargeAPIParams = {
+  sender: Address; // The address of the wallet paying
+  chainId: number; // The Chain ID of the payment Network (only Base is supported)
+  chargeId: string; // The ID of the Commerce Charge to be paid
+};
+
+export type PayTransaction = {
+  id: string; // The id of the Commerce Charge to be paid
+  callData: {
+    // Collection of fields used to make the contract call to the Payment contract
+    deadline: string; // Timestamp of when the payment will expire and be unpayable
+    feeAmount: string; // The amount of the processing fee in the recipient currency
+    id: string; // The id of the prepared transaction
+    operator: Address; // The address of the operator of the Payment contract
+    prefix: Address; // The prefix of the signature generated by Commerce
+    recipient: Address; // The address funds will settle in
+    recipientAmount: string; // The amount the recipient will get in the recipient currency
+    recipientCurrency: Address; // The address of the currency being paid (always USDC)
+    refundDestination: Address; // The wallet address of the payer
+    signature: Address; // The signature generated by the Payment contract operator, encoding the payment details
+  };
+  metaData: {
+    // Collection of metadata needed to make the contract call to the Payment Contract
+    chainId: number; // The chain this prepared transaction can be paid on
+    contractAddress: Address; // The address of the Payment contract
+    sender: Address; // The wallet address of the payer
+    settlementCurrencyAddress: Address; // The address of the currency being paid (always USDC)
+  };
+};
+
+/**
+ * Note: exported as public Type
+ */
+export type BuildPayTransactionResponse = PayTransaction | APIError;
diff --git a/src/api/utils/getPayErrorMessage.test.ts b/src/api/utils/getPayErrorMessage.test.ts
new file mode 100644
index 0000000000..1faaec0c45
--- /dev/null
+++ b/src/api/utils/getPayErrorMessage.test.ts
@@ -0,0 +1,36 @@
+import { describe, expect, it } from 'vitest';
+import {
+  GENERAL_PAY_ERROR_MESSAGE,
+  PAY_INVALID_CHARGE_ERROR_MESSAGE,
+  PAY_INVALID_PARAMETER_ERROR_MESSAGE,
+  PAY_TOO_MANY_REQUESTS_ERROR_MESSAGE,
+  UNCAUGHT_PAY_ERROR_MESSAGE,
+} from '../../pay/constants';
+import { getPayErrorMessage } from './getPayErrorMessage';
+
+describe('getPayErrorMessage', () => {
+  it('should return TOO_MANY_REQUESTS_ERROR_MESSAGE for errorCode -32001', () => {
+    const result = getPayErrorMessage(-32001);
+    expect(result).toBe(PAY_TOO_MANY_REQUESTS_ERROR_MESSAGE);
+  });
+
+  it('should return PAY_INVALID_CHARGE_ERROR_MESSAGE for errorCode -32601', () => {
+    const result = getPayErrorMessage(-32601);
+    expect(result).toBe(PAY_INVALID_CHARGE_ERROR_MESSAGE);
+  });
+
+  it('should return PAY_INVALID_PARAMETER_ERROR_MESSAGE for errorCode -32602', () => {
+    const result = getPayErrorMessage(-32602);
+    expect(result).toBe(PAY_INVALID_PARAMETER_ERROR_MESSAGE);
+  });
+
+  it('should return GENERAL_PAY_ERROR_MESSAGE for misc errorCode', () => {
+    const result = getPayErrorMessage(-32603);
+    expect(result).toBe(GENERAL_PAY_ERROR_MESSAGE);
+  });
+
+  it('should return UNCAUGHT_PAY_ERROR_MESSAGE for no errorCode', () => {
+    const result = getPayErrorMessage();
+    expect(result).toBe(UNCAUGHT_PAY_ERROR_MESSAGE);
+  });
+});
diff --git a/src/api/utils/getPayErrorMessage.ts b/src/api/utils/getPayErrorMessage.ts
new file mode 100644
index 0000000000..c269d82111
--- /dev/null
+++ b/src/api/utils/getPayErrorMessage.ts
@@ -0,0 +1,27 @@
+import {
+  GENERAL_PAY_ERROR_MESSAGE,
+  PAY_INVALID_CHARGE_ERROR_MESSAGE,
+  PAY_INVALID_PARAMETER_ERROR_MESSAGE,
+  PAY_TOO_MANY_REQUESTS_ERROR_MESSAGE,
+  UNCAUGHT_PAY_ERROR_MESSAGE,
+} from '../../pay/constants';
+
+export function getPayErrorMessage(errorCode?: number) {
+  if (!errorCode) {
+    return UNCAUGHT_PAY_ERROR_MESSAGE;
+  }
+
+  if (errorCode === -32001) {
+    return PAY_TOO_MANY_REQUESTS_ERROR_MESSAGE;
+  }
+
+  if (errorCode === -32601) {
+    return PAY_INVALID_CHARGE_ERROR_MESSAGE;
+  }
+
+  if (errorCode === -32602) {
+    return PAY_INVALID_PARAMETER_ERROR_MESSAGE;
+  }
+
+  return GENERAL_PAY_ERROR_MESSAGE;
+}
diff --git a/src/network/definitions/pay.ts b/src/network/definitions/pay.ts
new file mode 100644
index 0000000000..022ce66ab4
--- /dev/null
+++ b/src/network/definitions/pay.ts
@@ -0,0 +1 @@
+export const PAY_HYDRATE_CHARGE = 'pay_hydrateCharge';
diff --git a/src/pay/constants.ts b/src/pay/constants.ts
new file mode 100644
index 0000000000..0a820e71d6
--- /dev/null
+++ b/src/pay/constants.ts
@@ -0,0 +1,8 @@
+export const GENERAL_PAY_ERROR_MESSAGE = 'PAY_ERROR';
+export const PAY_UNSUPPORTED_CHAIN_ERROR_MESSAGE = 'UNSUPPORTED_CHAIN';
+export const PAY_TOO_MANY_REQUESTS_ERROR_MESSAGE =
+  'PAY_TOO_MANY_REQUESTS_ERROR';
+export const PAY_INVALID_CHARGE_ERROR_MESSAGE = 'PAY_INVALID_CHARGE_ERROR';
+export const PAY_INVALID_PARAMETER_ERROR_MESSAGE =
+  'PAY_INVALID_PARAMETER_ERROR';
+export const UNCAUGHT_PAY_ERROR_MESSAGE = 'UNCAUGHT_PAY_ERROR';