Samples NaAlHxD4-x (0 <= x >= 4) have been synthesized through a direct hydrogen isotope absorption/desorption cycles using Ti-doped NaAlH4 as source material, and then the interaction between hydrogen/deuterium and obtained NaAlHxD4-x and its hydrogen isotope effect were investigated. The results show that hydrogen isotope desorption/absorption kinetics of NaAlHxD4-x. is enhanced with increasing the hydrogen concentration. In addition, NaAlHxD4-x exhibits kinetics isotope effect during both hydrogen isotope desorption and absorption processes, and the isotope effect keeps stable during cycling. Our study may enable NaAlH4 to be used as hydrogen isotope separation material in future based on its kinetics isotope effect. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.