XPS represents a powerful tool for investigation of chemistry involved in chemical sensors, as analytes and recognition elements interact at a device surface, the region analyzed by the spectroscopic technique. In this way, the processes involved in preparation, operation and limiting life of sensors can be unraveled. Application of XPS to (bio)chemical sensors is reviewed with particular attention to electrochemical sensors, which account for more extensive literature. Systems based on polymers, organic mono/multilayers, carbon nanotubes and graphene, metallic species, also in the nanostructure format, and bioreceptors and relevant composites have been considered with a special focus on the information provided by XPS analysis on such (bio)sensing systems, highlighting the role played by XPS in sensor technology and giving at the same time an idea of what is still missing in this field thus advancing possible future uses of XPS in sensing technology. This journal is