The recent popularity of camera equipped mobile phones have sparked a new field of use for machine-readable 2D bar codes. A code can be printed on everyday items and be interacted with using a camera phone. The interaction is initiated by scanning the 2D bar code with the phone’s camera. And the reaction can be anything from simply retrieving information to triggering some action. Because of the low cost of printing 2D bar codes, there many possible applications that could be based on this. One such application is examined in this thesis and aims to improve the usefulness of normal cash register receipts. The idea is to print a 2D bar code on receipts that contains the purchase information in digital form. This is assumed to help customers with managing their receipts or with more detailed book-keeping. This assumption is evaluated by developing a prototype implementation of a receipt reader. This prototype is based on two Java libraries for decoding DataMatrix and Quick Response codes. The main conclusion from this evaluation is that the libraries used were able to store an estimate of 42 purchase items in a 2D bar code. There are tradeoffs that can be implemented to increase the capacity when needed which helps to make the assumption valid.