The phenomenon of evaporation of chromium oxide from chromium alloys oxidized at high temperatures was investigated by observing the loss in weight when pellets were heated at 1000°–1200°C in various atmospheres. Appreciable volatilization occurred in oxygen, more in wet oxygen, but none in argon or wet argon. specimens showed volatilization in none of these atmospheres. The results indicate that evaporation occurs by oxidation of to gaseous which dissociates to on redeposition. The mechanism by which moisture promotes volatilization was not established.