Through Auger electron spectroscopy (AES) and factor analysis (FA), we have studied the effect of metal-metal and metal-oxide interface interactions on the Ti oxide film formation. The passivation of Ti thin film oxidation is a thermally dependent process. It is possible, in consequence, to induce a further oxidation by heating the system. However, the complete oxidation of the thin film cannot be achieved in any case (for films thicker than 2 monolayers (ML)), due to substrate-Ti interactions. On the other hand, for the inverse configuration, metal over oxide, the strong Ti reactivity broadens the interface promoting the appearance of Ti2O3. (C) 2003 Elsevier Science B.V. All rights reserved.