Abstract: XPS has been widely used in many ames of materials science and engineering,especially in the situations with chemical changaes at surfaces or interface.In this paper,we willdiscuss the applications of XPS in three areas of materials research,including surace modificationof matorials,solid/solid interfaces and the interaction of materials with their environment,Approaches and the usefulness of XPS studies will be illustrated with specific examplesinvolving surfaCe modification of polymer and oxide materials,chemical and physical vapordeposition,studies of adhesion failure mechanisms, corrosion and tribology.