The initial rate of reaction of hydrogen and carbon monoxide was measured on supported Ru and Ni catalysts in a differential batch reactor. Using hydrogen adsorption to determine Ru and Ni surface areas, initial rates for methane and total hydrocarbon formation were expressed as turnover numbers. The initial rate of supported ruthenium was found to be independent of ruthenium particle size from < 10 to 90 Å. Nickel exhibited turnover numbers twice as high as Ru at 280 °C and activation energies of 20 and 28 kcal mole−1 for total hydrocarbon and methane formation compared to 17 and 24 kcal mole−1 for Ru.