Twenty percentage of Gd2O3-doped ceria solid solution has been prepared as an electrolyte for solid oxide fuel cells via the conventional mixed-oxide method from high-purity commercial CeO2 and Gd2O3. The solubility of Gd2O3 in CeO2 in the temperature range of 1300-1700degreesC has been examined based on the measurements of the lattice parameter. It is found that the dissolution of Gd2O3 in CeO2 is completed at 1600degreesC for 5 h. The addition of Gd2O3 increases sintering temperature, retards densification, and also depresses grain growth as compared with undoped CeO2. The sample sintered at 1550degreesC for 5 h has the highest grain boundary conductivity, while the highest grain interior conductivity is achieved for the sample sintered at 1600degreesC for 5 h. It is also observed that below 500degreesC, the maximum total conductivity is exhibited by the former sample, but above 500degreesC, for the latter one. (C) 2004 Elsevier B.V. All rights reserved.