Amorphous titania (TiO2) thin films were prepared on glass and silicon substrates by radio-frequency (r.f.) magnetron sputtering. These films were studied by choosing different substrate temperatures, r.f. powers, and annealing temperatures. High dielectric constants of 100-500 and varied dielectric losses were obtained. The dielectric properties of annealed titania films depended on the deposition conditions. As-deposited and annealed titania films with high dielectric constants and low losses were obtained for films deposited at 200 degreesC and 100 W and at 300 degreesC and 150 W Mechanical properties, such as internal stress and adhesion, of the titania films were evaluated. Optical properties, such as refractive index and optical transmittance, were also measured. To make a comparative study, aluminum titanate (Al2O3-TiO2) films prepared from a target with an Al2O3/TiO2 molar ratio of one were also studied.