The isothermal oxidation behavior of NiAl-28Cr-5Mo-1Hf alloy at 1000-1200 ℃ in air has been studied. The results show that isothermal oxidation kinetics of the NiAl-28Cr-5Mo-1Hf alloy obeys the parabolic law at all test temperatures. The microstructure and composition of the oxide layer have been studied by means of X-ray diffractometer, scanning electron microscope with an EDAX unit. The oxidation scale mainly consists of a-Al2O3, and there are also Cr2O3 and a little HfO2. The oxidation mechanism was disc...