Thin films of mixed oxides of CeO2-ZrO2 with molar ratio Ce/Zr = 0.73 have been prepared by sol-gel method. The precursor sols were obtained from a mixture of Ce(NH4)(2)(NO3)(6) titanium alkoxide (Zr(OPri)(4)) and isopropanol and then submitted to ultrasonic irradiation. The films were deposited using the dip-coating technique on ITO-Asahi glass and densified at 80 degrees C during 15 min and calcined at 450 degreesC during 15 min in oxygen atmosphere. Xerogels were characterized by thermal analysis (DTA-TG) and X-ray diffraction. Their possible use as ion storage (counter electrode) in electrochromic devices was studied by electrochemical (cyclic voltammetry and chronoamperometry) and optical measurements. The reversibility of the insertion/extraction process and the stability of the films as a function of the cycles number was performed.