Synchrotron-based scanning photoelectron microscopy has opened unique opportunities for exploiting processes occurring at surfaces and interfaces, which control the properties of functional materials where issues of complexity at microscopic length scales should be faced and understood. The present article aims at demonstrating the present capabilities of this microscopic method to explore the surface composition of micro- and nano-structured materials, focused on cases relevant to catalysis. We report and discuss some recent results about the chemical state of supported PtRh alloy microparticles under oxidation conditions and the changes in the status of a Co/polypyrrole electrocatalyst due to ageing in the course of the oxygen reduction reaction. Monitoring the lateral inhomogeneity in the chemical state at sub-micrometer length scales by combining chemical imaging and micro-spectroscopy has provided comprehension of events occurring at the catalyst surface, which determine the performance of the morphologically complex catalytic systems. Ongoing efforts for development and implementing of new set-ups that allow working closer to the realistic conditions of catalytic reactions are also outlined and briefly discussed.