In this study, an addition of Co oxide or Cu oxide to Sm0.2Ce0.8O1.9 (SDC) was studied to improve the sinterability of SDC. It has been found that both Co and Cu oxide are very effective as sintering aids, and the SDC sintering temperature can be reduced from 1400 degrees C without aids to below 1000 degrees C with only 1 at.% of either Cu oxide or Co oxide. As compared to the pure SDC, a slight decrease of ionic conductivity was observed in SDC with Cu sintering aid. There is no obvious effect on electrochemical property of SDC with Co sintering aid under 2.5 at.%. (c) 2006 Elsevier B.v. All rights reserved.