High-quality nanosized Ce0.8 Sm0.2-x Dyx O1.9 (0 ≤ x ≤ 0.15) powders were successfully synthesized by solution combustion method. Calcined Ce0.8 Sm0.2−x Dyx O1.9 (0 ≤ x ≤ 0.15) powders and sintered Ce0.8 Sm0.2−x Dyx O1.9 (0 ≤ x ≤ 0.15) pellets crystallized in the cubic fluorite structure. Dense and nanocrystalline Ce0.8 Sm0.2−x Dyx O1.9 electrolytes were fabricated, even at low sintering temperature (1300 °C). The microstructure and electrical property of the Ce0.8 Sm0.2−x Dyx O1.9 were discussed, depending on the Dy3+ content. The highest conductivity (0.053 S cm−1 at 800 °C) was obtained for Ce0.8 Sm0.17 Dy0.03 O1.9 .