La2Ni0.8Cu0.2O4+delta electrodes with different thicknesses were prepared on Ce0.8Sm0.2O1.9 electrolyte using screen printing technique. The electrocatalytic activity of La2Ni0.8Cu0.2O4+delta electrodes towards oxygen reduction reaction was investigated in comparison with La2NiO4+delta electrode. To understand the electrocatalytic activity of the two electrodes, chemical states of constituent elements on the surface of La2NiO4+delta and La2Ni0.8Cu0.2O4+delta were analyzed using X-ray photoelectron spectroscopy technique. La2Ni0.8Cu0.2O4+delta electrodes sintered at 920 degrees C exhibited improved electrocatalytic activity relative to literature results of the electrodes sintered at higher temperatures (e.g. 1200 degrees C). The Cu doping in La2NiO4+delta was validated to be effective in enhancing electrocatalytic activity. The electrocatalytic activity of La2Ni0.8Cu0.2O4+delta electrodes was found to be dependent on their thickness. Optimal electrocatalytic activity was achieved for the electrode with a thickness of 10 mu m, showing a polarization resistance of 0.13 Omega cm(2) at 800 degrees C. The effects of Cu doping and electrode thickness were diagnosed with respect to contributions of involved electrode reaction steps. The results of this work underscore that the electrocatalytic activity of La2Ni0.8Cu0.2O4+delta electrodes is dictated by dissociative adsorption process of molecular oxygen on the surface. (C) 2017 Elsevier B.V. All rights reserved.