Excess CaO type non-stoichiometric Ca1-xZrO3-delta (x = 0.2, -0.23) was prepared to investigate their impedance behavior in 500 degrees C-1100 degrees C temperature range. It was confirmed that grain plays predominantly role in total resistance and relaxation process. The grain boundary resistance decreases more rapidly than that of grain with the rising of temperature. The relaxation time was found reduces with temperature increases. The activation energies are calculated to be 1.19 eV of C1.2Z and 1.53 eV of C1.23Z. The excess CaO is suggested can enhance the resistance and relaxation process of grain boundary and gives rise to a higher activation energy of C1.23Z. By analyzing dielectric permittivity, polarization effect was verified works more seriously at higher temperatures especially in C1.2Z. The excess CaO was proved can relieve the polarization effect in C1.23Z. (C) 2012 Elsevier B. V. All rights reserved.