Abstract The fully-oxidized surface that forms on (1 1 1) oriented Ni 3Al single crystals, with and without Pt addition, at 300–900 K under oxygen pressures of ca. 10 −7 Torr was studied using XPS, AES, and LEIS. Two main types of surfaces form, depending upon oxidation temperature. At low-temperature, the predominant oxide is NiO, capped by a thin layer of aluminum oxide, which we refer to generically as Al x O y . At high-temperature (i.e., 700–800 K), NiO is replaced by a thick layer of Al x O y . By comparing samples that contain 0, 10 and 20 at.% Pt in the bulk, we find that the effect of Pt is to: (1) reduce the maximum amount of both NiO and Al x O y ; and (2) shift the establishment of the thick Al x O y layer to lower temperatures. Platinum also decreases the adsorption probability of oxygen on the clean surface.