In this work, we investigated the oxidation of titanium induced by O2 + ion bombardment using X-ray photoelectron spectroscopy (XPS). The analysis of photoemission spectra revealed significant transformations of the titanium electronic structure on the surface of the material during the oxidation process. Before exposing the sample to oxygen ions, the spectrum around the Ti 2p atomic level showed only the metallic phase of titanium. However, as bombardment time increased, the intensity of the peaks representing different titanium oxides (TiO, Ti2O3 and TiO2) increased, as well, indicating the progressive coverage of the titanium surface with oxide layers. After 180 minutes of bombardment with O2 + ions, the TiO2 phase becomes dominant, although metallic Ti and lower oxides are still present. These conclusions were confirmed by the analysis of photomission spectra around the valence band, which, with increasing oxygen irradiation time, showed a decreasing intensity of the peak characteristic for metallic titanium and an increase in the intensities of the peaks associated with the TiO2 valence band. The oxidation process was predominantly controlled by diffusion, with a parabolic growth rate of TiO2, consistent with Wagner's theory. Our analysis suggests that the mechanism of titanium oxidation is primarily influenced by the diffusion transport of Ti cations through singly charged cation vacancies, formed during the bombardment of the material.