The correlations of the microstructures and the electrical properties of high reactive Ce-0 8Sm0 2O1 (9) (SDC) powders, synthesized via an optimal carbonate coprecipitation method, were investigated. Microstructure of the SDC ceramics sintered at 900-1400 degrees C showed uniform grain and small grain size, compared with those prepared with various methods under similar sintering conditions. These features may be related to high conductivity (sigma(000 degrees C) = 0.022 S cm(-1)) and low activation energy for conduction (0 66 eV). AC impedance spectra were Involved to resolve grain interior and grain boundary resistance. Grain boundary contribution to the total resistance showed the values below 1/2 at 200-450 degrees C, suggesting low grain boundary effect. The motion enthalpy for the grain interior conduction decreased while the association enthalpy increased with sintering temperature up to 1300 degrees C, which might be possibly originated from the increase in lattice parameters with the sintering temperature (C) 2010 Elsevier Ltd. All rights reserved.