DY2O3 and La2O3-doped WO3 ceramics were fabricated by conventional ceramic technique and the microstructure, phase structure and electrical properties were studied. There are some porous slice-shaped materials in Dy-doped samples and club-shaped materials in La-doped samples. It is believed that slice-shaped materials (Dy-rich phase) are amorphism with weak conductivity to form the Schottky barrier. However, club-shaped materials (La-rich phase) are crystalline state with good conductivity so that the barrier is broken down, leading the nearly linear current-voltage characteristics. The grain boundary barrier layer capacitor (GBBLC) model cannot account for the high dielectric constant of La-doped sample because of the good conductivity of grain boundary materials. The high dielectric constant is assumed to arise from the high dielectric polarization of La-rich phase in the grain boundary. (c) 2005 Elsevier B.V. All rights reserved.