The temporal evolution of the surface chemistry of cubic TiAlN at 1 x 10(-3) mPa oxygen partial pressure and 300 K was analysed by means of X-ray photoelectron spectroscopy and by ab initio molecular dynamics simulations. Both the experimental and theoretical data imply that Ti and not Al determines the oxygen chemisorption process. Dissociative adsorption of oxygen is followed by upward movements of Ti, generating vacancies in the TiAlN interface and the formation of Ti-O-Ti bridges with Ti2O3-like bonding passivating the surface. (C) 2013 Elsevier B.V. All rights reserved.