Titanium oxide thin films are useful for applications such as catalysis, optical coatings, gas sensors, and other electronic devices. We have sputtered titanium in atmospheres of varying amounts of oxygen and argon; the resulting films were studied with x-ray photoelectron spectroscopy and x-ray diffraction in order to determine the changes in chemical composition. In addition, the thicknesses were measured for the purpose of finding the film growth rate versus oxygen content. We found that the films were composed of combinations of metallic titanium and three oxides. Metallic titanium and stoichiometric titanium oxide coexisted only in films grown with decreasing oxygen flow rates. Also, the highest stoichiometric TiO2 content in high-deposition rate films was obtained in the region of decreasing oxygen flow.