Experiments were conducted to investigate the reforming of organic compounds (primarily methanol) in supercritical water at 550-700degreesC and 27.6 MPa in a tubular Inconel 625 reactor. The results show that methanol can be completely converted to a product stream that is low in methane and near the equilibrium composition of hydrogen, carbon monoxide, and carbon dioxide. The effect of reactor temperature, feed concentration of methanol, and residence time on both conversion and product gas composition was investigated and the results are presented. Reaction pathway and potential applications of this technology are discussed. Ethanol and ethylene glycol resulted in less desirable effluent gas, with high concentrations of methane and carbon monoxide. Acetone and diesel fuel both resulted in the reactor becoming plugged. (C) 2003 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.