Perovskite type oxides Ln(0.6)Sr(0.4)Co(0.8)Mn(0.2)O(3-delta) (Ln = La, Gd, Sm, or Nd) have been prepared by the solid state reaction of corresponding oxides. The crystal parameters of the compositions were determined by XRD powder diffraction, which revealed that all the compositions have orthorhombic structure. The reaction test of all samples with Ce0.8Gd0.2O1.9 was carried out at 1200degreesC for 48 h, and no reaction product was detected by XRD. The change in mass of La0.6Sr0.4Co0.8Mn0.2O3-delta as a function of temperature was determined by thermogravimetric analysis (TGA). The electrical conductivity of the sintered samples were measured as a function of temperature from 200 to 1000degreesC. The highest conductivity of about 1400 S cm(-1) was found in La0.6Sr0.4Co0.8Mn0.2O3-delta. The cathodic polarization of these oxides electrodes deposited on Ce0.8Gd0.2O1.9 tablet was studied at 500-800degreesC in air. (C) 2003 Elsevier Ltd. All rights reserved.