Perovskite oxides SrCo1-yNbyO3-delta (SCNy, y = 0.00-0.20) are investigated as potential cathode materials for intermediate-temperature solid oxide fuel cells (IT-SOFCs) on La0.9Sr0.1Ga0.8Mg0.2O3-delta (LSGM) electrolyte. Compared to the undoped SrCoO3-delta the Nb doping significantly improves the thermal stability and enhances the electrical conductivity of the SCNy oxides. The cubic phase of the SCNy oxides with high thermal stability can be totally obtained when the Nb doping content y >= 0.10. Among the investigated compositions, the SrCo0.9Nb0.1O3-delta oxide exhibits the highest electrical conductivity of 461-145 S cm(-1) over the temperature range of 300-800 degrees C in air. The SCNy cathode has a good chemical compatibility with the LSGM electrolyte for temperatures up to 1050 degrees C for 5 h. The area specific resistances of SCNy with y = 0.10, 0.15 and 0.20 cathodes on LSGM electrolyte are 0.083, 0.099 and 0.110 Omega cm(2) at 700 degrees C, respectively. At y = 0.10. 0.15 and 0.20, the maximum power densities of a single-cell with SCNy cathodes on 300-mu m thick LSGM electrolyte achieve 675, 642 and 625 mW cm(-2) at 800 degrees C, respectively. These results indicate that SCNy perovskite oxides with cubic phase are potential cathode materials for application in IT-SOFCs. (C) 2009 Elsevier B.V. All rights reserved.