The oxidation of binary Co-10Cr alloys in 1 atm of pure O2 at 700 and 800°C was investigated. It indicated that the oxidation followed approximately the parabolic rate law (n=2). The parabolic rate constants as functions of temperature were 2.03×10-11, 7.05×10-10 g2cm-4s-1, respectively. The scales formed on Co-10Cr alloys were double-layered. The outer layer composed of large columnar CoO grains was relatively compact, while the inner CoO layer was porous, fine-grained and doped by cobaltous oxide CoO and spinel CoCr2O4.