The effects of copper oxide (CuO) addition on the crystal structure, densification and microstructure of Gd-doped ceria (Ce0.9Gd0.1O2 δ, CGO) synthesized by the polymeric precursor method have been studied. Ce0.9 xGd0.1CuxO2 δ (0rxr0.01) precursor powders were calcined at 600 1C for 1 h and the phase formation was studied by powder X-ray diffraction combined with Rietveld refinement analysis. Relative density measurements and microstructural analysis were performed on pellets sintered in the temperature range 1000–1100 1C in air. The effect of CuO as a sintering aid becomes more visible when its content is in the 0.5–1 mol% range where the relative densities are found to be 98% for sintering temperature as low as 1000 1C. A remarkable reduction (up to 500 1C) in the sintering temperature for 1 mol% CuO-doped CGO ceramics is observed together with the formation of a dissolved phase of Gd2O3–CeO2–CuO. Ce0.89Gd0.1Cu0.01 yO2 δ sintered at 1000 1C shows total electrical conductivity of 15.5 mS cm 1 at 600 1C slightly higher than Ce0.9Gd0.1O2 δ sintered at 1500 1C (12.4 mS cm 1).