This paper presents the results of the steam reforming of methanol on an as-prepared NiAl-layered double hydroxide catalyst pretreated in two different atmospheres and then the reaction at a high temperature of 390 degrees C with feed having various steam-to-methanol ratios. The product composition was found to vary significantly with the pretreatment atmosphere. High activity and stability with high selectivity for CO2 and H-2 and low level CO and no methane formation in a broad range of the H2O/CH3OH ratio was observed when the catalyst was preheated in the diluted H-2 stream. Whereas in the case of pretreatment in the reactive stream of the mixture of steam and methanol, the formation of methane and its increase with more steam in feed was obtained and with time on line the catalyst deactivated with an increase in CO formation and decreases in CO2, H-2 and CH4 production. A catalyst with optimal ratio of ionic Ni in different chemical environment is suggested to obtain an active, selective and stable reforming catalyst. (c) 2007 Published by Elsevier Ltd on behalf of the International Association for Hydrogen Energy.