Thin films of tungsten oxide, molybdenum oxide and mixed MoO3-WO3 oxides were obtained by atmospheric pressure chemical vapor deposition (CVD). All the films were prepared using identical technological parameters and through investigation of the optical properties of as deposited and annealed at 400degreesC a comparative study is reported. Raman, IR and VIS spectrophotometry and spectral ellipsometry methods were used. The mixed MoO3-WO3 films have higher optical absorption with maxima at a closer position with respect to the human eye sensitivity peak at 2.5 eV. The observed electrochromic effect is better expressed in the mixed films; the electrical charge inserted is higher. (C) 2002 Elsevier Science B.V. All rights reserved.