Recent results on characterization and applications of titania-silica materials as photocatalysts, acid catalysts and oxidation catalysts are reviewed. The similarities and differences in structural characteristics and physico-chemical properties between titania-silica mixed and supported oxides are emphasized. The generation of new catalytic active sites either on the silica surface or in the silica matrix is discussed with respect to the formation of Ti-O-Si bonds and the local structure. The insights obtained from these studies allow a fundamental understanding of the relationships between the structural characteristics and the physico-chemical/reactivity properties of titania-silica catalysts.