Many metal oxides effectively modify metallic aluminum (Al) powders to produce hydrogen in neutral water at room temperature. In this study, hydrogen is generated even more rapidly from the reacted solution when the by-product Al(OH)(3) (bayerite) is present. The influence of Al(OH)(3) on the hydrogen generation during the aluminum/water reaction is highly dependent on the surface area and the crystallinity of Al(OH)(3). High surface area and poor crystallinity of Al(OH)(3) render the system a rapid hydrogen generation rate. The self-catalytic phenomenon can be explained by the formation of AlO(OH) (boehmite) from the reaction of by-product beta-Al(OH)(3) and the surface passive oxide layer Al2O3. Furthermore, by taking advantage of the exothermic heat from the Al/water reaction, hydrogen yield is able to reach 70% within 30 min in a common aqueous solution (pH < 10) containing fine Al(OH)(3). This hydrogen generation technology relies on common, nontoxic, noncorrosive additives and is therefore a very promising system for creating a use-on-demand hydrogen source. (c) 2012 Elsevier B.V. All rights reserved.