A novel series of Gd1-xEu2xSm1-xZr2O7 (x=0, 1/3, 1/2, 2/3, 1) ceramics with a constant lattice parameter are prepared by solid-state reaction, and are then evaluated as possible solid electrolytes. The microstructure and electrical properties of Gd1-xEu2xSm1-xZr2O7 ceramics have been investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and complex impedance analysis. Gd1-xEu2xSm1-xZr2O7 ceramics exhibit a single phase of pyrochlore-type structure. The total conductivity of Gd1-xEu2xSm1-xZr2O7 ceramics obeys the Arrhenius relation, and gradually increases with increasing temperature from 723 to 1173 K. At 973-1173 K, the composition has little effect on electrical conductivity of Gd1-xEu2xSm1-xZr2O7 ceramics. Gd1-xEu2xSm1-xZr2O7 ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0 x 10(-4) to 1.0 atm at all test temperature levels. The maximum total conductivity of Gd1-xEu2xSm1-xZr2O7 ceramics is about 1.01 x 10(-2) S cm(-1) at 1173K in air. (C) 2011 Elsevier Ltd. All rights reserved.