To study anode materials for intermediate temperature solid oxide fuel cells with Ce0.8Sm0.2O1.9 (CSO) electrolyte using CO fuel, highly porous Ag-CSO cermets are prepared with MgO pore former and characterized. A single cell with 45Ag-CSO anode (Ag content: 45 wt%) is fabricated, tested, and compared with the similar cell with Cu-CeO2-CSO anode. The 45Ag-CSO cermet shows high porosity (47%). high electrical conductivity (1254 S cm(-1) at 923 K in CO), high activity (0.58 mmol(CO) min(-1) g(-1),) and stability for CO oxidation at 923 K, and no carbon deposition. The single cell with 45Ag-CSO anode shows high open circuit voltage (1.13 V at 923 K and 1.11 V at 973 K with pure CO as the fuel and air as the oxidant), high maximum power density (MPD, 178.4 mW cm(-2) at 923 K and 438.8 mW cm(-2) at 973 K), and high stability (no apparent change in MPD over 100 h test at 973 K). This cell is much better in performance than the cell with Cu-CeO2-CSO anode. Given that the CSO electrolyte is 0.385 mm thick, the performance is very encouraging. All the results suggest that the porous 45Ag-CSO cermet is an excellent anode material for ITSOFC with CSO electrolyte using CO fuel. (C) 2008 Elsevier B.V. All rights reserved.