In this study, for the first time, we studied the adsorption and subsequent dissociative reaction of hydrazine borane (N2H4BH3, HB) over the pristine and Al-doped boron nitride nanotubes (BNNTs) by means of density functional theory calculations. The nature of the interaction between the HB and tube surface is investigated by electron density difference and charge-transfer analyses. Our results reveal that the HB molecule can be strongly adsorbed on the exterior surface of the pristine and Al-doped BNNTs with noticeable adsorption energies and charge transfers. Also, the Al-doping tends to increase the calculated adsorption energies. Several possible pathways for HB decomposition over these surfaces are proposed. The most probable reaction channel that generates a H-2 molecule is endothermic over both surfaces and needs relatively large activation energy. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.