Tungsten trioxide (WO3) has been found to be a very versatile material for electrochromic (EC) devices. It behaves as a mixed ion conductor and hence it has recently attracted much interest in the field of solid state ionics. When the intercalation of the film is taken in the cyclic voltammograms for various concentrations (0.1, 0.5 and 1.0 N) of H2SO4, the voltage is recorded for the peak current. The powder X-ray diffraction pattern is taken and the peaks are compared with the JCPDS values. It is found to be the triclinic structure. The FT-IR spectra are taken for the WO3 films electrodeposited at different deposition current densities (0.25, 0.50, 0.65 and 0.75 mA/cm(2)) keeping the other deposition parameters like pH of the solution, concentration of the electrolyte and temperature of the bath constant. The film exhibits a broad peak from 3780 to 3500 cm(-1) which indicated the OH-H stretching vibration. The peak at 3543 cm(-1) depends upon the coloration increase in the electrodeposited tungsten trioxide film. A little amount of molecular water may exist in the electrodeposited WO3 film, which corresponds to a broad peak at 2500 cm(-1). A small peak at 820 cm(-1) exhibits W-O stretching. After ion intercalation the peak positions are slightly changed. (C) 2002 Elsevier Science B.V. All rights reserved.