[en] A thin film (approx. 30 nm) of anodic hafnium oxide on hafnium is analysed by sputtering with 3 keV Ar+ ions and Auger electron spectroscopy (AES). Changes observed in the Auger line-shape of hafnium during the ion bombardment are interpreted as formation of new oxide phases caused by sputtering induced depletion of oxygen in the surface. (author)