Polycrystalline powders of BaCe(0.9)Ln(0.1)O(3-delta) (Ln = La, Nd, Sm, Gd, Yb, Tb and Y) have been prepared using a freeze-drying precursor route at 1000 degrees C. In order to decrease the densification temperature, different sintering aids (e.g. Co, Zn, Ni, Fe and Cu) were added by mixing the polycrystalline powders with a nitrate solution containing these metals. This allows obtaining dense ceramics at temperatures as low as 1000 degrees C, when compared to samples without sintering aids at 1400 degrees C. The effect of aid content and sintering temperature on the microstructure and electrical conductivity were investigated by scanning electron microscopy and impedance spectroscopy. The addition of small amounts of transition metals does not produce observable structural changes by conventional X-ray powder diffraction. However, the bulk and total conductivities decrease when compared to samples without transition metals. Zn seems to be the most effective sintering element for BaCe(0.9)Ln(0.1)O(3-delta) electrolytes because it does not cause significant changes in the ionic and electronic conductivities. (C) 2011 Elsevier B.V. All rights reserved.