Thin films of CeO72-TiO2-ZrO2 with 23 mol% of Ce, 45 mol% of Ti and 32 mol% of Zr were obtained by the sol-gel method. The precursor sol was prepared from a mixture of Ce(NH4)(2) (NO3)(6), Ti(OPri)(4) and Zr(OPri)(4) solubilized in isopropanol and then sonicated. Xerogels were characterized by Differential Scanning Calorimetry (DSC) and Thermal Gravimetric Analysis (TGA) and X-ray diffraction. The films were deposited by dip-coating technique on a glass plate coated with an indium tin oxide film (ITO) and thermally treated at 80 degreesC for 15 min. and heated at 450 degreesC for 15 min in an oxygen atmosphere. By means of the addition of a lithium salt (LiCF3SO3) to the precursor solution, films with different electrochemical performances were obtained. Their possible use as ion storage (counter-electrode) in electrochromic devices (ECD) was analyzed by spectroelectrochemical measurements using cyclic voltammetry and chronoamperometry coupled to spectrometric measurements. (C) 2004 Elsevier B.V. All rights reserved.