The highly phase-pure perovskite electrolyte, La(0.9)Sro(0.1)Ga(0.8)Mg(0.115)Co(0.085)O(2.85) (LSGMCO), was prepared by means of glycine-nitrate process (GNP) for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The perovskite phase evolution, sintering, electrical conductivity and electrochemical performance of LSGMCO were investigated. The results show that the highly phase-pure perovskite electrolyte LSGMCO can be obtained after calcining at 1150 degrees C. The sample sintered at 1450 degrees C for 20 h in air exhibited a better sinterability, and the relative density of LSGMCO was higher than 95%. The stoichiometric indexes of the elements in the sintered sample LSGMCO determined experimentally by EDS were in good agreement with the nominal composition. The electrical conductivities of the sample were 0.094 and 0.124 S . cm(-1) at 800 degrees C and 850 degrees C in air, respectively. The ionic conduction of the sample was dominant at high temperature with the higher activation energies. While at lower temperature the electron hole conduction was predominated with the lower activation energies. The maximum power densities of the single cell fabricated with LSGMCO electrolyte with Ce0.8Sm0.2O1.9 (SDC) interlayer, SmBaCo2O5+x cathode and NiO/SDC anode achieved 643 and 802 mW cm(-2) at 800 degrees C and 850 degrees C, respectively. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.