The present work focuses on the study of different Ruddlesden-Popper based cathode materials for Solid Oxide Fuel Cells at Intermediate Temperature (IT-SOFC). The partial substitution of La and Ni by Pr and Co, respectively, were studied in the La(2-x)A(x)Ni(1-y)ByO(4+delta) system, with the purpose of enhancing their mixed ionic-electronic conductivity and the electrocatalytic activity for the O-2-reduction while the crystal structure was preserved. All synthesized compounds were characterized by electrochemical impedance spectroscopy (EIS), DC conductivity measurements, X-Ray diffraction (XRD), iodometric titration and scanning electron microscopy (SEM). XRD analyses by Rietveld refinement revealed the influence of the ionic radius on the crystalline phase for the different dopants, i.e., variation of the cell parameters and M-O bond lengths. The substitution in both La and Ni sites improves La2NiO4+delta electrochemical properties as IT-SOFC cathode, since higher conductivity and lower polarization resistance were obtained. Finally, La1.5Pr0.5Ni0.8Co0.2O4+delta cathode exhibited the lowest electrode polarization resistance and activation energy values in the temperature range of 450-900 degrees C. La1.5Pr0.5Ni0.8Co0.2O4+delta was applied on an anode supported cell and a maximum power density of similar to 400 mW cm(-2) was obtained at 700 degrees C using pure hydrogen and air. (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.