The dynamics and energetics related to the release of chemisorbed hydrogen from small diameter single-walled carbon nanotubes is investigated by first-principles molecular dynamics simulations. Our results suggest a possible route for thermally-activated desorption of hydrogen from the nanotube sidewall, leading to formation of molecular H-2, and shed light on the basic mechanisms of the reversible storage of hydrogen in carbon nanotubes. In agreement with recent experiments, simulations, indicate carbon nanotubes as suitable materials for the reversible storage of hydrogen. Moreover, calculations point to the restoration of the it bond patterning of the sidewall as the driving force for the desorption of hydrogen from carbon nanotubes. (c) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.