Differential steam-reforming rates were measured for methane, ethane, n-butane, n-hexane, 2,4-dimethylhexane, n-octane, cyclohexane, benzene, and toluene over 1wt.% Pd/ceria between 620 and 770K and were compared to rates observed on 1wt.% Pd/alumina and 1wt.% Pt/ceria. The H 2 O:C ratios at which stable rates were observed on Pd/ceria depended on the hydrocarbon, varying from less than 1:1 for methane to 3:1 for 2,4-dimethylhexane. In the series of alkanes from methane to n-hexane, for a H 2 O:C ratio of 2:1, the only products were CO, CO 2 , and H 2 O and the rate of formation of CO 2 and CO increased with carbon number. Benzene was also selectively converted to CO x and H 2 , but at lower rates than the alkanes with the exception of methane. For 2,4-dimethylhexane and n-octane, a significant amount of cyclohexane was observed in the initial products and cyclohexane was selectively converted to benzene at low conversions. Steam reforming of toluene also gave benzene as the initial product. FTIR measurements of Pd/ceria under methane-steam-reforming conditions indicate the formation of carbonates on the ceria. Pd/alumina showed significantly lower rates than Pd/ceria and much lower CO 2 :CO ratios in the initial products, implying ceria plays an important role in the reaction. Pt/ceria gave rates and selectivities that were essentially identical to that of Pd/ceria. The implications of these results for hydrocarbon fuel processing are discussed.