Anodic oxide formed on a Ti-Nb-Sn alloy was analyzed by angle-resolved X-ray photoelectron spectroscopy (XPS) to determine the chemical state and composition of the uppermost surface. The anodic oxide formed on the alloy consisted of TiO2, SnO2, and Nb2O. The cationic fractions of Nb2O5 and SnO2 were lower than the atomic fractions of Nb and Sn in the alloy, and the uppermost surface contained higher concentrations of these oxides. The photo-induced change in the amount of carbon contaminants adsorbed on its surface was also analyzed by XPS combined with in situ ultraviolet (UV) light illumination. The variations in the chemical state induced by the UV light illumination were consistent with those on monolithic TiO2. (C) 2012 Elsevier B.V. All rights reserved.