A TiN coating, deposited by PVD, was rubbed against corundum balls in a laboratory fretting experiment for different number of cycles. The surface composition and chemical state of the wear tracks, debris found on the TiN coating and the transfer layer on the corundum counterbody were determined with X-ray photoelectron spectroscopy and Auger electron spectroscopy. The worn surfaces in all the wear tracks are depleted in oxygen when compared to a native surface, but are similar for the different fretting cycles. The transfer layer seems to be composed mainly of TiO2. The debris is also enriched in TiO2. The results indicate that the friction peak in TiN-corundum fretting experiments is not due to chemical differences in the wear tracks or at the surface of the transfer layer. (C) 1999 Elsevier Science S.A. All rights reserved.