Coupon specimens of 30Nb-40Al-(30-x)Cr-xMo (mol %), with x being 0, 7.5, 15, 22.5 or 30, and of 30Nb-40Al-(22.5-y)Cr-7.5Mo-ySi, with y being 5 or 10, were oxidised in air in a temperature range 1473 to 1773 K for 72 ks. The influence of additions of 0.05 and 0.1% Hf to 30Nb-40Al-22.5Cr-7.5Mo was also examined. Conventional metallographic examinations were performed for the specimens before and after the oxidation. The major phase of the specimens is AlNbCr, and their minor phases are Cr(2)Al and NbAl(3), except for high Mo-content specimens which form AlNbMo, Nb(2)Al, Mo(3)Al and MoAl(3). The additions of Si lead to additional formation of Nb(5)Si(3). Virtually Al(2)O(3) scales (a dense and continuous Al(2)O(3) layer with a thin layer consisting of AlNbO(4), CrNbO(4) and/or SiO(2) on it) are formed at temperatures up to 1673 K, except for the high Mo-content specimens which form poorly protective scales. The additions of Hf increase the mass gain to some degree. 5Si forrns protective scales at temperatures up to 1723 K, and 30Cr and 10Si up to 1773 K.