Surfaces of platinum, palladium, and nickel metals and metal oxides treated with arsine at room temperature have been studied with x-ray photoemission spectroscopy. It is found that arsine decomposes readily on platinum, palladium, and nickel metal surfaces to form arsenic alloys. The resulting electronic structures of the treated surfaces are similar to those of the alloys of platinum, palladium, and nickel with sp metals: (1) reduction in the core level line-shape asymmetry, (2) narrowing of the valence d band and shifting of the band away from the Fermi level, (3) considerable shifts of the Auger lines to lower kinetic energies, and (4) reduction of the intensity of the core-level satellites and increase of their separation from the main peaks. At room temperature, arsine reacts with PtO2 and PdO, and reduces them to Pt-As and Pd-As alloys. However, NiO does not react with arsine.