The hydrogen storage properties of MgH2-xwt%TiCN (x=5, 10, 15) composites weresystematicallyinvestigated andthe results show that the addition of TiCN can effectively improve the de/rehydrogenation kinetics of MgH2. Taken the onset dehydrogenation temperature and isothermal de/rehydrogenation kinetics into consideration, the MgH2-10 wt% TiCNcompositewas shown to have the best performance.It was found that the MgH2-10 wt% TiCNcomposite couldrelease 4 wt% H2 in 17.3 min at 300 °C while the as-synthesized MgH2could not release any hydrogen under the same condition. Besides, the MgH2-10 wt% TiCNcompositecould absorb 4.63 wt% H2 under 3.2MPa hydrogen pressure at 300°Cwithin 20s. Compared with as-synthesized MgH2, the activation energy of the MgH2-10 wt% TiCN compositewas significantly decreased from 183.76 kJ/mol to 106.82 kJ/mol.XRDanalysisrevealed that theTiCN remained stable during the ball millingand the following de/rehydrogenation cycle. The catalytic mechanism was also proposed that the TiCN particles absorbed on MgH2not only served as chargetransfer centers and accelerated the hydrogen incorporation and dissociation rate but also provided more diffusion channels for hydrogen, which contributedto the good de/rehydrogenation properties of MgH2.