Vanadium and tantalum-doped vanadium pentoxide, V2O5 and V2O5:Ta thin films (2.5 and 5 mol% of Ta) were prepared using sol-gel dip-coating technique. The coating solutions were prepared by reacting vanadium (V) oxytripropoxide and tantalum ethoxide (V) as precursors using anhydrous isopropyl alcohol as solvent. The films were deposited on a transparent glass substrate with ITO conducting film by dip-coating technique, with a withdrawal of 20 cm/min from the vanadium-tantalum solution and heat treated at 300 degrees C for 1 h. The resulting films were characterized by cyclic voltammetry, optical spectroscopy and by X-ray diffraction analysis (XRD). XRD data show that the films thermally treated at 300 degrees C were crystalline. A charge density of 70 mC/cm(2) was obtained for the film with 5 mol% of Ta, with an excellent stability up to 1500 cycles. (c) 2005 Elsevier B.V. All rights reserved.