Nanoparticulate catalysts infiltrated into solid oxide fuel cell (SOFC) electrodes can significantly enhance cell performance, but the stability of these electrodes has been an open issue. An infiltration procedure is reported that leads to stable scandia-stabilized zirconia (SSZ) cathode electrode performance. An SSZ cathode, infiltrated with 50 - 150 nm lanthanum-strontium manganate electro-catalyst particles, is shown to be voltage-stable for over 500 h of operation at 650 C, at a controlled current density of 150 mA/cm(2). This demonstrates the potential viability of nanoparticulate-infiltrated electrodes for commercial SOFCs, and illustrates the functional stability of nanoparticulate catalysts in the demanding environment of SOFC electrodes. (c) 2007 The Electrochemical Society.