Experimental work was carried out to study the effect of process variables on the mechanism of oxidation of Cr 3B 4 in air. Nickel and cobalt were used as metallic binders with weight percentages ranging from 1% to 20%. The experiments covered a temperature range from 400 to 1000°C and time periods of up to 5 hours. It was found that the use of nickel as a binder gave the best results as it improves the thermal stability of chrome boride cermets at 8 wt.% Ni or more. The mechanism of the oxidation and the rate-controlling steps were determined. In addition, the activation energies for the initial oxidation were calculated. In general, increasing the binder content, increased the thermal stability.