Here, effects of B-site transition metals (TMs) in the (La0.6Sr0.4)XO3-delta (X = Mn, Fe, Co) perovskite structure on the activity and stability of the oxygen electrodes during high temperature electrolysis are discussed to provide a deep understanding of the phenomena observed for different oxygen electrodes under anodic polarizations. Performance and stability of the electrodes vary significantly at 800 degrees C as the TMs changed from Mn to Fe and Co, which is attributed to the different ionic conductivities and surface chemistry of the materials that have a strong dependence on the valence state and electronic structure of TMs. Under an anodic current passage of 200 mA cm(-2) at 800 degrees C, electrode polarization resistance (R-E) and overpotential (eta) of the (La0.6Sr0.4)MnO3-delta (LSM) electrode decrease significantly by 1.75 Omega cm(2) and 101 mV during the 1200 min test, compared with the constant values of R-E and eta for the (La0.6Sr0.4)FeO3-delta (LSF) and (La0.6Sr0.4)CoO3-delta (LSC) and electrodes, an indication of the influence of B-site TMs on the electrode performance and stability. Most serious degradation is observed at the (La0.6Sr0.4)MnO3-delta electrode due to the electrode detachment arising from the accelerated SrO surface segregation and related disintegration of LSM particles near the electrode electrolyte interface. (C) 2017 Elsevier B.V. All rights reserved.