The effects of CuO-V2O5 addition on the sintering temperature and microwave dielectric properties of ZnO-Nb2O5-TiO2-SnO2 were investigated. The CuO-V2O5 addition lowered the sintering temperature of ZnO-Nb2O5TiO2-SnO2 ceramics effectively from 1150 to 860 degrees C due to the liquid-phase effect Of Cu2V2O7 and Cu-3(VO4)(2), as observed by XRD. The microwave dielectric properties were found to strongly correlate with the sintering temperature and the amount Of CuO-V2O5 addition. The maximum Qf values decreased with increasing CuO-V2O5 content, due to the formation of the second phase, Cu-3(VO4)(2) and CuNbO3. Zero tau(f) value can be obtained by properly adjusting the sintering temperature. At 860 degrees C, ZnO-Nb2O5-TiO2-SnO2 ceramics with 1.5 wt.% CuO-V2O5 gave excellent microwave dielectric properties: epsilon(r) = 42.3, Qf = 9000 GHz and tau(f) = 8 ppm/degrees C. (C) 2005 Elsevier Ltd. All rights reserved.