Ceria electrolytes co-doped with Gd3+ and Y3+ (Ce0.8Gd0.2-xYxO1.9) were synthesized by GNP. The crystal structures, lattice parameters and crystallite sizes were determined by XRD. The morphology of the powders was observed by TEM. Sintered at 1250oC for 4 h, all die-pressed ceria pellets achieved densities higher than 95% of theoretical values. The ionic conductivities were measured using AC impedance technique and Ce0.8Gd0.05Y0.15O1.9 showed a higher ionic conductivity than those of other compositions at 500-750oC, indicating that it is an attractive electrolyte material for IT-SOFC.