Composites containing La0.8Sr0.2Cr1-xRuxO3-delta (LSCrRu) with x-0-0.25 and Gd0.1Ce0.9O1.95 (GDC) were studied as anodes in solid oxide fuel cells (SOFCs) with La0.9Sr0.1Ga0.8Mg0.2O3-delta, (LSGM) electrolytes. Electrode polarization resistance R-p decreased during initial SOFC operation before reaching a minimum. The decrease was more rapid, and the ultimate R-p value reached was generally lower, with increasing temperature and Ru content x. R-p was stable at longer times except for x=0.25 where it increased slightly. SOFCs with x=0.18 anodes at 800 degrees C yielded power densities as high as 0.53 W/cm(2) with an R-p value, including the (La,Sr)(Co,Fe)O-3-GDC cathode, of <0.15 Omega cm(2). Transmission electron microscopy revealed Ru nano-particles on LSCrRu surfaces: their size increased and their density decreased with increasing temperature. Increasing the Ru content increased the density of Ru surface particles at a given time and temperature. Measured early-stage Ru surface coverage values were consistent with a model where Ru supply to the LSCrRu surface was limited by Ru bulk out-diffusion, but the coverage saturated at longer times. There was surprisingly little Ru particle coarsening over times up to 1000 h at 800 degrees C, with Ru particles sizes remaining <10 nm. The cell R-p values generally decreased with increasing Ru nano-particle surface area. (C) 2008 Elsevier B.V. All rights reserved.