Pure and doped TiO2 thin films were obtained by r.f. sputtering method. The samples were deposited onto glass and glass covered with indium tin oxide (ITO) substrates. Phase and surface morphology were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The structure of TiO2 thin films is influenced by the substrate used and also by doping with Ce, Nb and Fe impurities. Consequently, the transmittance will also be modified.