Molecular oxygen adsorption on several ternary silicides (Ti4M4Si7, M=Ni,Co) and (TiFeSi2) is studied using photoemission. The valence band spectrum shows that the O2dissociates on adsorption and suggests that an exposure of a few hundred langmuirs is sufficient to completely cover the surface with a layer of atomic oxygen. Si 2pcore‐level spectra show that oxygen bonds with the silicon and photoemission peaks from all oxidation states of silicon are observed. 3pcore levels from the metallic elements like titanium do not show core‐level components indicating the formation of metal–oxygen bonds. The bonding of oxygen to silicon could be due to silicon termination of the surface or maybe due to energetics which favor silicon–oxygen bond formation over metal–oxygen bond formation, the breaking of silicon–silicon bonds rather than silicon–metal bonds or the breaking of the fewest atomic bonds.