TiO2 based nanustructured coatings have been prepared by sol-gel method on glass and SiO2/glass substrates. The films were thermally treated in oxidative and reductive conditions at 500 degreesC. The influence of the substrate and of the thermal treatment on the optical properties of the films was studied. The samples were characterized by spectroscopic ellipsometry (SE), scanning electron microscopy (SEM), Rutherford backscattering spectroscopy (RBS) and Raman spectroscopy. SE results supported by other optical and structural measurements have proven the transformation of CuO from as-prepared samples into Cu2O in samples heated in oxidative conditions and into metallic Cu in samples heated in reductive conditions as well as the transformation of the amorphous TiO2 in anatase. (C) 2004 Elsevier B.V. All rights reserved.