Abstract The microstructure and nonlinear current-voltage characteristics of ZnO-V 2O 5 ceramics sintered at 900 °C were investigated. V 2O 5 was the only additive used and the amount ranged from 0.25 to 2 mol%. According to our microstructural observations, a change of grain-growth mechanism occurred from the isotropic growth behavior of pure ZnO to the abnormal growth after doping with V 2O 5. This was attributed to the sintering of ZnO grains in the presence of a V 2O 5-rich liquid phase. The zinc oxide ceramics doped with V 2O 5 exhibited nonohmic behavior. The nonlinear characteristics of these binary ceramics were strongly dependent on the V 2O 5 content and the microstructure.