X-ray photoelectron spectroscopy (XPS) has been employed to investigate titanium oxynitride (TiN(x)O(y)) films prepared by d.c. magnetron sputtering using air/Ar mixtures, which allows one to perform the deposition at a high base pressure (1.3 x 10(-2) Pa) and can reduce substantially the processing time. XPS analyses revealed that all the prepared TiN(x)O(y) films comprised Ti-N, Ti-N-O, and Ti-O chemical states. When the air/Ar ratio was below 0.3, nitrogen-rich TiN(x)O(y) films were obtained. As the air/Ar ratio was above 0.4, oxygen-rich TiN(x)O(y) films were formed. XPS depth profile analyses were also performed in selected specimens. It has been found that at relatively low air/Ar ratios, such as 0.5, the oxygen content of the films increased toward the film/substrate interface and when the air/Ar ratio was higher. TiN(x)O(y) films with large oxygen content with uniform concentrations were then formed. (c) 2009 Elsevier B.V. All rights reserved.