Nonohmic behavior is obtained for polycrystalline ZnO with copper as the only additive in the range 0.3x1 wt%. The effect of copper on the microstructure and electrical behavior of ZnO:Cu ceramics is investigated. The leakage current decreases and the breakdown electric field increases as the copper concentration increases. The large apparent dielectric constant of ZnO:Cu ceramic (k>>kZnO,kZnOis the dielectric constant of pure ZnO) is attributed to the grain boundary barrier layer effect. A Schottky barrier height of 0.27–0.46 eV is obtained for various copper‐added samples, depending on sintering temperatu