The oxidation behaviour of a β-NiAl material (produced by powder metallurgy) was investigated in the temperature range 1200°C < T < 1400°C. In isothermal runs at 1200 and 1400°C, an alumina scale grew according to a parabolic growth law. At 1300°C, catastrophic oxidation was observed, but a short anneal at low oxygen partial pressure at 1200°C, prior to the oxidation at 1300°C, initiated a parabolic scale growth. Further, cyclic oxidation tests were carried out and the growth mechanism of the scale was identified by two-stage oxidation (16O2/18O2) in combination with SNMS isotope profile analysis.