Tungsten oxide hydrate films of WO3 center dot H2O and WO3 center dot(H2O)(0.33) were prepared on conductive glass substrates by anodic deposition in aqueous 0.01-0.5 mol/L WO42- solutions. Structural and optical characterizations were carried out by X-ray photoelectron spectroscopy, X-ray diffraction, SEM observation, optical absorption measurements, and photoelectrochemical measurements. The films composed of large WO3 center dot H2O grains with square shapes, which was obtained in the 0.01-0.09 mol/L WO42- solutions, possessed a bandgap energy of approximately 2.5 eV, and the granular-WO3.(H2O)(0.33) films, which was obtained in the 0.05-0.5 mol/L WO42- solutions, showed 3.3 eV in bandgap energy. The WO3 center dot H2O-WO3 center dot(H2O)(0.33) mixtured films prepared in the 0.01-0.09 mol/L WO42- solutions showed a photoresponse for visible light at 380-600 nm, due to the presence of 2.5 eV-bandgap WO3 center dot H2O.(C) 2017 Elsevier B.V. All rights reserved.