A thermodynamic analysis of the steam reforming of representative oxygenate fuels, including methanol, ethanol, n-propanol, n-butanol, n-hexanol, ethylene glycol, glycerol, glucose, acetic acid, and acetone, was carried out with the Gibbs free-energy minimization method. The operational regime, energy efficiency, and reformate composition of reforming various oxygenate fuels were studied. It was revealed that the critical steam/carbon ratio, by which there is free carbon deposition in the reforming product, decreases with an increasing oxygen/carbon ratio in oxygenate fuels. The appropriate operating temperature range for steam reforming of oxygenate fuels is within 600-700 degrees C. Fuels with a higher hydrogen/carbon ratio have wider operational windows. The results would offer a guideline toward a rational selection of raw materials for a renewable reformer proton-exchange membrane fuel cell system based on understanding features of oxygenate fuels in the steam-reforming process.