TiO2 electrochromic thin films have been prepared by reactive de magnetron sputtering under various conditions and their electrochromic properties have been investigated by using I M LiClO4 in propylene carbonate as an electrolyte. Total pressure was found to be the most important parameter to control the electrochromic properties of sputtered TiO, films. The sample deposited under high pressure conditions (8-10 Pal) showed good electrochromic properties; its visible transmittance changed from 14% (colored state) to 81% (bleached state) and the coloration efficiency was 29 cm(2)/C.