The suggestion has been made in the literature that solid oxide fuel cells (SOFCs) operated with syngas as fuel may be viable in certain gas ratio regimes. We have explored this hypothesis with a promising bimetallic anode material. SOFCs with Ni0.7Co0.3-YSZ cermet anodes were operated with CO/H-2 mixtures in the full concentration range. Electrochemical impedance spectroscopy and voltammetry measurements were employed to measure the exchange current density (i(0)) values of each fuel mixture. The fuel mixtures of CO/H-2 ratios corresponding to the range 20/80 and 30/70 were found to have i(0) values larger than that of pure H-2 with the same cell. For these two fuel ratios, an improvement of 5-8 times, respectively, in the exchange current density has been observed. Higher CO/H-2 fuel ratios in the range of 60/40-80/20 produced i(0) values lower than H-2, as carbon poisoning is operational in this region. Continuous running of a cell with fuel ratio 25/75 CO/H-2 for 7 days produced i(0) values above the values for pure H-2 as has been recently suggested. (C) 2011 Elsevier B.V. All rights reserved.