The present work is aimed at investigating hydrogen transport through amorphous WO3(a-WO3) and crystalline WO3(c-WO3) films prepared by rf-magnetron sputtering onto indium tin oxide(ITO) glass under impermeable boundary condition in 0.1 M H2SO4solution by using Fourier transform infra-red(FTIR) spectroscopy, cyclic voltammetry, potentiostatic current transient technique and ac-impedance technique. The FTIR spectra showed that thea-WO3film contained water, apart from thec-WO3. From the results obtained form the electrochemical experiments, it was suggested that the different behaviours in cyclic voltammograms betweena-andc-WO3films result from an open-structured nature ofa-WO3film containing H2O, which does not exist in thec-WO3film and there are three kinds of hydrogen injection sites in the films, i.e., reversibly active site, shallow trap site(reversible trap site) and deep trap site(irreversible trap site). The Mott-Schottky approach permitted us to semi-quantitatively determine the amount of the deep trap site.