The tungsten oxide (WO3) film was grown by dip coating-pyrolysis method with the PEG-400 as the structure-directing agent. Microstructure of the WO3 film was characterized by TG-DSC, XRD and SEM techniques. It was found that the film annealed at 350 degrees C for 2 h comprised cubic WO3 and orthorhombic WO3. The measurements of the cyclic voltammetry (CV) and UV-vis spectrum suggested that the WO3 film had a good electrochromic reversibility performance. The film possessed excellent modulation to the visible light and the maximal average transmittance modulation reached 70.06%. (C) 2007 Elsevier B.V. All rights reserved.