Nano-sized BaCe0.8Sm0.2O3-delta and Cu-doped BaCe0.8Sm0.2O3-delta proton conducting electrolyte powders are synthesized by citric-nitrate method, and then the powder properties are investigated. The synthesized BaCe0.8Sm0.2O3-delta powder acquires pure perovskite structure after heat treatment above 1100 degrees C, while impurity phases such as BaCO3 and Ce0.8Sm0.2O2-delta are formed below 1100 degrees C. The BaCe0.8Sm0.2O3-delta and Cu-doped BaCe0.8Sm0.2O3-delta showed similar powder characteristics, except the shrinkage rate. The sintering temperature for densification of the synthesized BCS are significantly reduced as much as similar to 300 degrees C by small amount of Cu. Compared to drastic reduction in sintering temperature, the total conductivity and the activation energy of Cu doped BCS turn out to deviate negligibly from those of pure BCS. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.