Titanium-silicon binary oxide thin films of differing TiO2\ content were prepared by using an ionized cluster beam (ICB) deposition method using multi-ion sources under a dry preparation process. From the results of UV-vis absorption measurements, binary oxide thin films with low TiO2 content showed much higher transmittance as compared with the pure TiO2 thin film, indicating that the Ti-oxide species of these Ti-Si binary oxide thin films exist in a highly dispersed state within the SiO2 matrices. Ti K-edge XAFS measurements revealed that such binary oxide thin films with low TiO2 content (less than 20%) showed only a sharp preedge peak attributed to the highly dispersed Ti-oxide species which are different from the peaks of anatase TiO2 thin films. Moreover, they were found to exhibit much higher and more efficient photocatalytic reactivity for the decomposition of NO into N-2 and O-2 under UV light irradiation than the pure TiO2 thin films.