2D-gel electrophoresis is widely used in combination with MALDI-TOF mass spectrometry in order to analyse the proteome of biological samples. It can be used to discover proteins that are differentially expressed between two groups (e.g. two disease conditions) obtaining thus a set of potential biomarkers. Biomarker discovery requires a lot of data processing in order to prepare data for analysis or in order to merge data from different sources. This kind of work is usually done manually, being highly time consuming and distracting the operator or researcher from other important tasks. Moreover, doing this repetitive process in a non-automated, handling-based manner is error-prone, affecting reliability and reproducibility. To overcome these drawbacks, the S2P, an AIBench based desktop multiplatform application, has been specifically created to process 2D-gel and MALDI-mass spectrometry protein identification-based data in a computer-aided manner. S2P is open source and free to all users at http://www. sing-group.org/s2p.