The rates of aqueous-phase reforming of methanol and ethylene glycol to form H-2 and CO2 were measured under kinetically controlled reaction conditions at temperatures of 483 and 498 K over alumina-supported platinum catalysts. Results show that the rates of formation of H-2 from aqueous solutions of methanol (from 1 to 10 wt%) are similar to the rates of conversion of ethylene glycol, suggesting that C-C bond cleavage is not rate limiting for ethylene glycol reforming. Aqueous-phase reforming of both oxygenated hydrocarbons over Pt/Al2O3 leads to nearly 100% selectivity for the formation of H-2 (compared to the formation of alkanes), suggesting that methanation or Fischer-Tropsch reactions involving CO/O-2 and H-2 do not appear to be important over platinum-based catalysts under the conditions of the present study. The rate of production of hydrogen is higher order in methanol (0.8) compared to ethylene glycol (0.3-0.5), and the reaction is weakly inhibited by hydrogen (-0.5 order) for both feedstocks. The rates of aqueous-phase reforming of methanol and ethylene glycol show apparent activation barriers of 140 and 100 kJ/mol, respectively, from 483 K and 22.4 bar total pressure to 498 K and 29.3 bar total pressure. Low levels of CO (< 300 ppm) are detected in the gaseous effluents from aqueous-phase reforming of methanol and ethylene glycol over alumina-supported Pt catalysts, suggesting that water-gas shift processes are operative under the aqueous-phase reforming conditions of this study. The observed reaction kinetics for ethylene glycol of this study can be explained by a reaction scheme involving quasi-equilibrated adsorption of ethylene glycol, water, H-2, and CO2, combined with irreversible steps involving dehydrogenation of adsorbed ethylene glycol to form adsorbed C(2)O(2)Hx* species, cleavage of the C-C bond to form adsorbed COHy* species, further dehydrogenation leading to adsorbed CO*, and removal of adsorbed CO* by water-gas shift. Aqueous-phase reforming of methanol may take place by a similar reaction scheme, without the step involving cleavage of the C-C bond. The nearly first-order reaction kinetics with respect to methanol can be explained by weaker adsorption of methanol compared to molecular adsorption of ethylene glycol. (C) 2003 Elsevier Science (USA). All rights reserved.