The effect of the Cr poisoning on the electrochemical properties of NdBaCo2O5+delta cathode for IT-SOFCs was investigated by the electrochemical impedance spectroscopy (EIS) and the cathodic polarization analysis. With the Cr poisoning, the area-specific resistances (ASRs) increased at 500-600 degrees C and did not increase with the increasing temperature. The Cr poisoning made a negative effect on the oxygen reduction reaction (ORR) below 600 degrees C. Besides, the Cr poisoning decreased the exchange current density i(o). The activation energies of io were higher than those of the ASRs, indicating that the charge transfer process was the rate-determining step for the ORR. With or without the Cr poisoning, the polarization curves were independent of the on the sweep rate, indicating that there were no mass transport limitations on the ORR rate. Hence, the Cr poisoning deteriorated the charge transfer process of the ORR for NdBaCo2O5+delta and decreased the ORR activity. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.