In this study, the sol-gel spin-coating method has been used to make Ta2O5-CeO2 thin films. These films have been prepared in various composition ratios to observe changes in their optical and structural properties. Reflectance and transmittance spectra were collected in the spectral range of 300-1000 nm and were accurately fit using the Tauc-Lorentz model. Film thicknesses, refractive indices, absorption coefficients, and optical band gaps were extracted from the theoretical fit. The highest refractive index value was found at 5% CeO2 doping. The structure of the films was characterized by X-ray diffractometry and Fourier transform infrared spectrometry, while the surface morphology was examined through atomic force microscopy. (C) 2007 Elsevier B.V. All rights reserved.