Addition of small amounts of H-2 to the combustion chamber of spark ignition internal combustion (IC) engines can result in increased fuel efficiency and lower emissions. Hydrogen can be generated by decomposition of alcohols, which are now present in a large fraction of automobile fuels (reformulated gasoline). In the present study, in situ production of hydrogen by catalytic decomposition of ethanol and other alcohols over Cu/Al layered double hydroxide (LDH) derived catalysts has been investigated. Reactions were performed using both neat alcohols and alcohol/fuel mixtures at temperatures of 150-400degreesC and atmospheric pressure. Catalytic dehydrogenation of the neat alcohols to H-2 and their corresponding aldehyde appears to be the major mechanism occurring in the reactions. The active catalytic phase is derived from the initial Cu/Al LDH structure during the process. The onset of H-2 formation generally occurred at 200-230 degreesC, and is related to the formation of metallic Cu species formed during in situ modification of the initial LDH. In alcohol/fuel mixtures, dehydrogenation of the alcohols also appeared to be the major mechanism. Significant irreversible catalyst deactivation occurred above 350-360 degreesC. (C) 2003 Elsevier Science B.V. All rights reserved.