The oxidation is one of the major corrosion processes of metals. Copper and copper alloys have wide industrial applications, and therefore are of interest for studies of oxidation mechanism, particularly in the Cu 2 O formation. We proposed the collision-induced absorption (CIA) mechanism for the oxidation of Cu with hyperthermal O 2 molecular beam (HOMB) in our early studies. Here, we introduce our recent studies of the oxidation of Cu(410) and Cu(511) stepped surfaces and various Cu 3 Au surfaces with HOMB. On the Cu stepped surface, we discuss the role of defects on the CIA mechanism in the oxidation. The Cu Au alloys are an ideal system for investigating the formation of protective layer against further oxidation into bulk. On the various Cu 3 Au surfaces, we demonstrate how the protective layer against the CIA oxidation is formed. Finally, we introduce shortly the steric eŠects in the reaction of NO on Si (111).