The aim of the study was to find how the microstructure of a titanium alloy changes during oxidation. In order to accomplish this task, the microstructure of the oxide scales formed on TAW, Betacez and Ti3Al intermetallic alloys during annealing in air at 900degreesC for 170 h was examined using scanning electron microscopy (SEM). It has been found that the oxide scales have a multilayer structure. The chemical compositions of the scales were determined, and an attempt was made to identify the individual phases. The significant differences in the phase composition of the scales were quantified. The intermetallic Ti3Al alloy seems to be most resistant to the oxidation at a temperature of 900 degreesC. (C) 2003 Elsevier Science B.V. All rights reserved.