A quick, simple route was established for producing boehmite nanofibers by direct reaction between activated aluminum and hot water. Naturally, an oxide layer around aluminum particles prevents aluminum core to react with water. In the present work, the oxide layer was destroyed, using mechanical energy, to facilitate the reaction. Hot water increased the kinetic of reaction which accelerates hydrogen generation rate at the interface of aluminum and just-produced layer of boehmite, whose outward flow prohibits passive boehmite layer from being formed on aluminum particles. Boehmite particles suspended in water were self-assembled using no surfactant and/or template, constructing a fiber structure with a diameter less than 10 nm and an average length of 150 nm in less than 40s. Average crystallite size of resultant fibers was 4.3 nm and its specific surface area was about 283.6 m(2)/g. (C) 2010 Elsevier B.V. All rights reserved.