Different amounts of silver (3-15 wt.% Ag2O) have been mixed with ceramic powders based On La1.7Sr0.3Mo2O9-delta (LSM). XRD analysis indicated that the silver was chemically stable in LSM. TEM observation and XPS analysis showed that some metallic silver atoms presented random distribution in the LSM ceramic, while others entered into crystal lattice in the form of Ag+, efficiently stabilizing the cubic phase at the room temperature. And there were a great enhancement on conductivity in Ag added (<10 wt.% Ag2O) LSM ceramics. Also addition of Ag had a significant influence on the surface oxygen exchange properties with electrode components. (C) 2012 Elsevier Ltd. All rights reserved.