A consistent set of rate constants describing simultaneous H-2 and CO adsorption and electro-oxidation in a proton exchange membrane fuel cell with high-performance membrane electrode assemblies is reported. The parameters were estimated from regression of a first-principles model to anode overpotential data collected at 70 and 90 degrees C at 101 and 202 kPa. A Langmuir isotherm was found to be sufficient for the CO adsorption equilibrium for this catalyst when the Heyrowski-Volmer mechanism for H-2 oxidation on a Pt/Ru-C catalyst is used. These parameters and the ability to predict performance loss that are critical as standards for hydrogen quality are established. (C) 2008 The Electrochemical Society.