In this work was studied the electrochemical response of La(2)Nia(4+delta) Fa compound by impedance spectroscopy measurements. This compound is a potential cathode material to be used in Solid Oxide Fuel Cell (SOFC). The area specific resistances (ASR) of a La2NiO4+delta/YSZ/La2NiO4+delta symmetrical cell were determined between 600 and 800 degrees C. The ASR values increases with time suggesting a chemical reaction between the cells components. Reactivity studies were carried out between La2NiO4+delta and both YSZ and CGO electrolytes. The reactivity studies were performed by means of two different tests: La2NiO4+delta films deposited onto both electrolytes and heated at 900 degrees C for 72 h (Pellet Test), and intimate mixture of La2NiO4+delta with either YSZ or CGO powders were heat treated at 900 degrees C during 2 h (Powders Test). In each case the reaction products were evaluated by XRD. Both studies suggest a high reactivity between the electrode (La2NiO4+delta) and the electrolytes (YSZ, CGO). (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.