Transition metal oxides exhibit electrochromic effect, under a small voltage they transfer from transparent state to colored one and if voltage polarity is turned back, they bleach again. Oxide coatings possess this ability, but in order to exhibit it, they should be part of a multilayer system-electrochromic device. Atmospheric pressure chemical vapour deposition technology was used for preparation of mixed MoO3-WO3 films, utilizing thermal decomposition of tungsten and molybdenum carbonyls mixture in oxygen atmosphere. Surface morphology of the films was studied by Field emission scanning electron microscopy (FESEM). Micro Raman spectroscopy was applied for studying crystalline structure and X-Ray photoelectron spectroscopy (XPS) revealed the chemical composition of the mixed oxide thin films. The films of MoO3-WO3 show improved electrochromic characteristics compared to single oxide films, especially when the mixed films are in as deposited state and possess amorphous structure. (C) 2010 Elsevier B.V. All rights reserved.