Solid solutions of Ce0.85Y0.13Pr0.02O2-delta were prepared by the co-precipitation and mixing of powder techniques and characterized by several techniques. The main purpose of this work was to evaluate the effect of the minority solute dispersion on the microstructure and electrical conductivity of this solid electrolyte. Praseodymium oxide co-doping of ceria-yttria produces changes in the crystallite size and in the average grain size of sintered pellets. Microstructural characterization shows that solid electrolytes with high homogeneity were obtained by the co-precipitation technique. Energy dispersive analysis and Raman spectroscopy results showed the formation of a Pr-rich solid solution of cerium oxide and praseodymium oxide in specimens prepared by the mixing of powder technique. Impedance spectroscopy results are dependent on the microstructure and show significant differences in the intergranular conductivity of sintered pellets prepared by different methods. (c) 2005 Elsevier B.V. All rights reserved.