The oxidation of (W,Mo) powders has been investigated at 400, 500 and for 12.0 hours in air. It was shown that the low temperature oxidation resistance of (W,Mo) was worse than that of , and they showed great changes in mass, volume and colour. Especialy at , the amount of volume expansion of (W,Mo) was as high as about times and color changed from black to yellow after 4.0h with , , (W,Mo) and amorphous as main reaction products. The mass gain and oxidation rate were relatively slower at and than that at .