COSTO (Anti-COrrosion thin films for anodic STructural elements in prOton exchange membrane water electrolysers) is part of the French “Programme et Equipements Prioritaires de Recherche” for clean hydrogen generation (PEPR-H2). It is a collaboration between six French research labs including the LPS. Its goal is to create coatings for the structural elements that make up the bipolar plates and porous transport layers of the anode compartment of proton exchange membrane electrolysers (PEMWE) with thin anti-corrosion layers to ensure greater durability and lower costs. A detailed analysis of the anti-corrosion properties and micro/nanostructure of these coatings is under way. Studies of their performance and durability under real-world conditions is also crucial. The STEM group’s role is to characterize, via STEM imaging and core-loss EELS, the structure and chemistry of the thin-film coatings (TiN, TiOxN1-x, SnO2…) before and after exposition to the corrosive PEMWE environment.