La0.8Sr0.2Co0.5Fe0.5O3-delta(LSCF) cathodes infiltrated with electrocatalytically active Pd and (Gd,Ce)O-2 (GDC) nanoparticles are investigated as high performance cathodes for the O-2 reduction reaction in intermediate temperature solid oxide fuel cells (IT-SOFCs). Incorporation of nano-sized Pd and GDC particles significantly reduces the electrode area specific resistance (ASR) as compared to the pure LSCF cathode: ASR is 0.1 Omega cm(2) for the reaction on a LSCF cathode infiltrated with 1.2 mg cm(-2) Pd and 0.06 Omega cm(2) on a LSCF cathode infiltrated with 1.5 mg cm(-2) GDC at 750 degrees C, which are all significantly smaller than 0.22 Omega cm(2) obtained for the reaction on a conventional LSCF cathode. The activation energy of GDC-and Pd-impregnated LSCF cathodes is 157 and 176 kJ mol(-1), respectively. The GDC-infiltrated LSCF cathode has a lower activation energy and higher electrocatalytic activity for the O-2 reduction reaction, showing promising potential for applications in IT-SOFCs. (C) 2009 Published by Elsevier B.V.