Effect of a MgF2 catalyst, prepared by ball-milling, on the hydrogen desorption ability of commercial MgH2 was investigated. When MgH2 was catalyzed with a MgF2 composite, it exhibited good cyclability and sharp faceting, with a small grain size (around 10 nm), which differs from those of pure MgH2. The addition of the MgF2 catalyst suggests that the F anion could significantly contribute to the cyclability of Mg particles and aid in the inhibition of MgH2 grain growth. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.