Mixed oxides from the TiO2-WO3 system were prepared as polycrystalline materials. Their phase composition and electrical conductivity were investigated using X-ray diffraction (XRD) and dc electrical measurements. The energy gap, evaluated on the basis of optical measurements, was presented as a function of W concentration. The influence of chemical composition on structural, semiconducting and optical properties of the TiO2-WO3 polycrystalline ceramics was discussed. (C) 2004 Elsevier Ltd. All rights reserved.