In this paper, ceria codoped by samaria (Sm2O3) and scandia (Sc2O3) (ScxSm0.2-xCe0.8O1.9, x = 0, 0.01, 0.02, 0.04, 0.06, 0.08, SSDCX) was prepared by the glycine-nitrate method and investigated as candidates for electrolyte materials of intermediate temperature solid oxide fuel cells (IT-SOFCs). The influence of scandia addition on the phase composition, crystalline structure, microstructure, electrical conductivity and chemical stability of the ceria based electrolytes was investigated. Cell performances with Sc0.04Sm0.16Ce0.8O1.9 as electrolytes were also tested and compared with those of cells with Sm0.2Ce0.8O1.9 as electrolytes. The results indicate that ceria codoped with proper amount of Sc2O3 and Sm2O3 have higher electrical conductivity than ceria only doped with Sm2O3. The doping amount of Sc2O3 also has influence on the electrical conductivity of the SSDCX materials, and the highest electrical conductivity of 2.64 x 10(-2) S cm(-1) is achieved for Sc0.04Sm0.16Ce0.8O1.9 materials at 700 degrees C. Single cells with Sc0.04Sm0.16Ce0.8O1.9 as electrolytes demonstrate a maximum power density of 225 mW cm(-2), and an open circuit voltage (OCV) of 0.87 Vat 700 degrees C. Codoping Sc2O3 and Sm2O3 also suppresses the reduction of ceria thus inhibits the drop of OCV under working condition at 700 degrees C. (C) 2015 Published by Elsevier B.V.