La0.84Sr0.16MnO3-delta-Bi1.4Er0.6O3 (LSM-ESB) composite cathodes are fabricated by impregnating LSM electronic conducting matrix with the ion-conducting ESB for intermediate-temperature solid oxide fuel cells (IT-SOFCs). The performance of LSM-ESB cathodes is investigated at temperatures below 750 degrees C by AC impedance spectroscopy. The ion-impregnation of ESB significantly enhances the electrocatalytic activity of the LSM electrodes for the oxygen reduction reactions, and the ion-impregnated LSM-ESB composite cathodes show excellent performance. At 750 degrees C, the value of the cathode polarization resistance (R-p) is only 0.11 Omega cm(2) for an ion-impregnated LSM-ESB cathode, which also shows high stability during a period of 200 h. For the performance testing of single cells, the maximum power density is 0.74 W cm(-2) at 700 degrees C for a cell with the LSM-ESB cathode. The results demonstrate the ion-impregnated LSM-ESB is one of the promising cathode materials for intermediate-temperature solid oxide fuel cells. (C) 2009 Elsevier B.V. All rights reserved.