In view of utilization as cathodes for intermediate temperature solid oxide fuel cells (SOFCs), the La2-xSrxNiO4 +/-delta (x = 0.2 and 0.8, delta > 0) series of compounds were evaluated with respect to their electrical conducting, thermomechanical and electrochemical properties. On the one hand, La1.2Sr0.8NiO4-delta exhibits a higher electrical conductivity (>180 S cm(-1) in the temperature range 600-800 degrees C) and a lower electrode polarization under open-circuit voltage conditions (similar to 0.12 Omega cm(2) at 800 degrees C) than La(1.8)Sro(0.2)NiO(4+delta), together with a suitable thermal expansion coefficient (13.8 x 10(-6) K-1 averaged between 50 and 1000 degrees C). On the other hand, the structure and electrochemical properties of La1.2Sr0.8NiO4-delta electrode were obviously changed after being subjected to cathodic polarization. The cathodically polarized La1.2Sr0.8NiO4-delta electrode showed an aggregation of strontium oxide onto the surface, concomitant with a degradation of electrochemical properties. By contrast, the structure and electrochemical properties of La1.8Sr0.2NiO4+delta electrode before and after cathodic polarization were basically unvaried. The disparate changes in structure and electrochemical properties of the two electrodes were interpreted in terms of their differing peculiarities in oxygen nonstoichiometry. The results of this work highlight the importance of strontium content and thereby oxygen nonstoichiometry of La1-xSrxNiO4 +/-delta electrodes to their structural stability under cathodic polarization conditions, which is a critical point to be used as cathodes in SOFCs. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.