Impedance spectroscopy with millimeter-scale electrodes was used to determine the local grain-boundary resistivity (rho(gb)) of a 1-mol%-Al2O3-doped CaO-stabilized ZrO2 (CSZ) specimen. A much higher rho(gb) at the specimen surface was observed compared with that of the specimen interior. The result was mainly due to the difference in the dihedral angle of the intergranular phase, which was similar to20degrees at the surface and similar to100degrees at the interior.