---
title: "Cancel a transaction"
url: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/key-steps-c-library/cancel-or-refund-a-transaction-c-library/cancel-a-transaction-c"
source_url: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/key-steps-c-library/cancel-or-refund-a-transaction-c-library/cancel-a-transaction-c.md"
canonical: "https://docs.adyen.com/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/key-steps-c-library/cancel-or-refund-a-transaction-c-library/cancel-a-transaction-c"
last_modified: "2026-05-24T12:54:31+02:00"
language: "en"
---

# Cancel a transaction

[View source](/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/key-steps-c-library/cancel-or-refund-a-transaction-c-library/cancel-a-transaction-c.md)

Use this function to cancel a transaction that is actively being processed on the PED. For transactions that have already been processed by the Adyen payments platform, use [Refund a transaction from the POS - C](/point-of-sale/classic-library-deprecation/classic-library-integrations/c-library-integration/key-steps-c-library/cancel-or-refund-a-transaction-c-library/refund-a-transaction-from-the-pos-c).

## Function

| Name                 | Description                                                                                                                                                                                         |
| -------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `cancel_transaction` | Call this function to cancel a transaction. The POS application must never assume the final state and should wait for the final state of the transaction as reported by the PED (from the library). |

### Parameters

| Name               | Description                                |
| ------------------ | ------------------------------------------ |
| `terminal_id`      | The terminal ID of the PED.                |
| `tender_reference` | A reference for the transaction to cancel. |

### Code example

The declaration of the call to cancel a transaction is:

```cpp
ADYEN_RESULT cancel_transaction(char * terminal_id, char *tender_reference)
```