We report the growth of thin films of Ta2O5 doped with TiO2 on Si (1 0 0) substrates at low temperatures by a new photoinduced sol-gel process. Polymeric sols were formed through hydrolysis and condensation of tantalum ethoxide mixed with titanium isopropoxide. These were then spin-coated on the substrates and irradiated by Xe-2* excimer lamps operating at a wavelength of 172 nm. The chemical bonding changes in the thin films were analysed by Fourier transform infrared spectroscopy (FTIR), which confirmed densification of the films and the removal of H2O and OH groups after some 10 min irradiation at 300 degreesC. Layer thicknesses between 18-140 nm were readily achievable by this technique whose refractive index, it, increased from 1.6 after spin on to 2 after irradiation. Film thickness and refractive index were found to be dependent on exposure time, substrate temperature and film composition. Maximum values of n were recorded at a TiO2 content of 8%.