In this study, the hydrogen storage properties of MgH_2-X wt% K_2NiF_6(X = 5, 10, 15, 20, and 50) were investigated for the first time. From the analysis of the onset desorption temperature and isothermal de/absorption kinetics, it was shown that MgH_2+ 5 wt% K_2NiF_6sample has the best performance. The 5wt% doped sample started to release hydrogen at about 260 °C, which was a reduction of about 95 °C and 157 oC compared with the as-milled and as-received MgH_2. In addition, the de/absorption kinetics of the MgH_2+ 5 wt% K_2NiF_6 were also improved significantly compared to the un-doped MgH_2. The apparent activation energy for hydrogen desorption exhibited the decrement from 167.0 k J/mol for as-milled MgH_2 to 111.0 k J/mol with the addition of 5 wt% K_2NiF_6. Moreover, the X-ray diffraction spectra displayed the formation of new phases of KF, KH, Mg_2Ni and Mg_2NiH_4 by doping the K_2NiF_6with MgH_2 after the dehydrogenation and rehydrogenation processes. The scanning electron microscope results revealed that MgH_2 doped with 5 wt% K_2NiF_6demonstrated the smallest particle size compared to the as-received and as-milled MgH_2. It is believed that the formation of in situ active species of KF, KH, and Mg_2Ni could provide a synergetic catalytic effect in enhancing the hydrogen sorption properties of MgH_2. From the analysis of the onset desorption temperature and isothermal de / absorption kinetics (X = 5, 10, 15, 20, and 50) were investigated for the first time. , it was shown that MgH_2 + 5 wt% K_2NiF_6 sample has the best performance. The 5 wt% doped sample started to release hydrogen at about 260 ° C, which was a reduction of about 95 ° C and 157 ° C compared with the as-milled and as -received MgH_2. In addition, the deactivation kinetics of the MgH_2 + 5 wt% K_2NiF_6 were also significantly weaker than the un-doped MgH_2. The apparent activation energy for hydrogen desorption exhibited the decrement from 167.0 kJ / mol for as- milled MgH_2 to 111.0 k J / mol with the addition of 5 wt% K_2NiF_6. Furthermore, the X-ray mapping spectra displayed the formation of new phases of KF, KH, Mg_2Ni and Mg_2NiH_4 by doping the K_2NiF_6 with MgH_2 after the dehydrogenation and rehydrogenation processes The scanning electron mic roscope results revealed that MgH_2 doped with 5 wt% K_2NiF_6demonstrated the smallest particle size compared to the as-received and as-milled MgH_2. It is believed that the formation of in situ active species of KF, KH, and Mg_2Ni could provide a synergetic catalytic effect in enhancing the hydrogen sorption properties of MgH_2.