Controlled growth of titanium oxide films by sequential surface chemical reactions was studied using a novel vapor combination of tetrachlorotitanium (TiCl4) and hydrogen peroxide (H2O2). Optical constants and thicknesses of these films were investigated in terms of growth temperature and vapor pressures by using a variable-angle spectroscopic ellipsometer. Growth rates were almost constant at approximately 0.065 nm cycle(-1) (= 0.65 nm min(-1)) for substrate temperatures from 340 degrees C to 490 degrees C. Indices of refraction were also constant at 2.6 in almost the same temperature range.