Thin films of the mixed CdO-TiO2 system were prepared on glass substrates using the sol-gel technique. The precursor solution was obtained starting from the mixture of two precursor solutions of CdO and TiO2 prepared separately. The Ti and Cd atomic concentrations in the precursor solution, X and (1-X), respectively, were varied in the range 0.20 <= X <= 0.65. The films were sinterized at 450 degrees C in open atmosphere. X-ray diffraction and photoacoustic spectroscopy techniques were used for characterization. The films present predominantly the Monteponite cubic phase of CdO for X <= 0.30, and the Ilmenite rhombohedrical crystalline phase of CdTiO3 for X > 0.30. The energy band gap (E-g) as a function of X was analyzed, and the maximum E-g = 3.70eV was observed when X = 0.5. (c) 2006 Published by Elsevier B.V.