Sol-gel derived silica-titania films, containing 0-30 mol% TiO 2 , were prepared by spin-coating and heat treated at temperatures up to 900°C. They were studied by X-ray photoemission (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The number of oxygen atoms in Si O Ti and Ti O Ti bonds was found to vary from 0 to 25% as the TiO 2 content increased from 0-30 mol%. The fraction of these oxygen atoms also increased with heat treatment temperature, to 700°C, for the 80SiO 2 -20TiO 2 base composition, showing a continuous increase in both Si O Ti hetero-condensation and Ti O Ti home-condensation bonding sequences.