We examined first-principle calculation to investigate hydrogen adsorption mechanism on a carbon nanotube (CNT) in which aluminum nanowire was wrapped. The adsorbed hydrogen atoms were stabilized on inner and outer walls of the Al-doped CNT. Hydrogen chemisorptions occurred on inner and outer sides of the Al-doped CNT with 2.81 and 2.93 eV of the binding energy, respectively. These energies were larger than those of the CNT without Al atoms. We also carried out the molecular dynamics (MD) simulations and found that a H atom doped in the Al-doped CNT moved along the axis when a H atom had more than about 4 eV of the kinetic energy. Furthermore the adsorption and desorption mechanism of a H-2 molecule on the CNT surface was studied by the MD simulation. The electronic properties of the systems described above were discussed in terms of quantum energy densities. (c) 2006 Elsevier B.V. All rights reserved.