Co-free La0.6Sr0.4FeO3-delta (LSFNbo) and La0.6Sr0.4Fe0.9Nb0.1O3-delta (LSFNb0.1) perovskite oxides were prepared by a standard solid-state reaction method. The structural stability and electrochemical performance of La0.6Sr0.4Fe0.9Nb0.1O3-delta as both cathode and anode were studied. Nb dopant in LSFNbo significantly enhances the structural and chemical stability in anode condition. At 800 degrees C, the polarization resistances (Rp) of LSFNb0.1 symmetric electrode based on YSZ electrolyte are 0.5 and 0.05 Omega cm(2) in H-2 and air, respectively. The peak power densities of LSFNb0.1 based on LSGM electrolyte-supported SSOFCs are 934 and 707 mW cm(-2) at 850 degrees C in H-2 (3% H2O) and dry CO, respectively. Moreover, the symmetric cell exhibits reasonable stability in both H-2 and CO fuel, suggesting that La0.6Sr0.4Fe0.9Nb0.1O3-delta may be a potential symmetric electrode material for hydrogen and carbon monoxide SOFCs. (C) 2019 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.