Titanium dioxide (TiO2) thin films were deposited on glass substrate by d.c. magnetron sputtering at 200 degrees C substrate temperature. The thicknesses of the films were measured using stylus type profilometer. The deposited films were annealed using rapid thermal annealing (RTA) system in the O-2 ambient for 20 min at 400 and 500 degrees C. Influence of Ar/O-2 flux ratio and annealing temperature on structural and optical properties of the samples was analyzed using X-ray diffraction (XRD) and UV-vis spectrometer in the range of 200-1100 nm. The films annealed above 400 degrees C were crystalline with anatase phase, whereas at the as-deposited states, the films were amorphous. Optical properties such as band gap, refractive index and absorption coefficient were calculated using transmittance spectra of the samples. The influence of thermal annealing on structure and optical properties is discussed. Band gap energies of the TiO2 films were also determined using photoluminescence (PL) measurements. Copyright (C) 2010 John Wiley & Sons, Ltd.