Multilayer films based on tungsten oxide (WO3) were deposited by reactive dc magnetron sputtering onto glass substrates for electrochromic (Ee application. The configuration of the smart EC devices (ECDs) or window is ITO (Indium-tin- oxide)/WO3/Li+-electrolyte/counter electrode film/ITO. Depending on the choice of different counter electrodes such as SnO2, V2O5, ZrO2 and the doped Mo (or Fe) films, a total of 16 window structures were fabricated and studied. The multilayer ECD between two pieces of glass exhibited maximum optical transmittance of 84 % and minimum of 16% before and after applying 5 V voltages for 2 seconds (or in bleached and coloured state) in visible light range. Without glass substrate the multilayer exhibited a maximum of 97 % transmittance at bleached state.