Hydrogen for current polymer electrolyte membrane (PEM) and alkaline fuel cells must be supplied with not more than a few tens of ppm of CO or CO2, respectively. If the hydrogen is generated, as it is used, it must be produced efficiently over a broad fuel cell demand range. and follow load changes on the order of seconds. We generated hydrogen for a broad variety of demands from a 1.09/1 molar mix of methanol/water using a commercial water-gas shift catalyst and a membrane reactor. The reactor output hydrogen was fed directly into a PEM fuel cell. Demand was varied between 0 and 0.9 A/cm(2), both in flow through operation and in dead-end operation. We found power densities virtually identical to those with bottled gas. We also demonstrated inherent load following on a time scale less than or equal to2000 mus. (C) 2003 Elsevier Science B.V. All rights reserved.