Using ab initio calculations we investigated the hydrogen storage in single-walled boron nitride nanotubes. We present the nature of hydrogen interaction in selected sites of a (5,5) and (9,9) BN nanotube. Our results show that BN nanotubes are preferable to carbon nanotubes for hydrogen storage applications due to their heteropolar binding nature of their atoms. In addition, by increasing the nanotube's diameter-decreasing its curvature, more efficient binding energies of hydrogen can be achieved. (c) 2006 Elsevier B.V. All rights reserved.