The catalytic effects of MnFe 2 O 4 nanoparticles on the hydrogen storage properties of MgH 2 −LiAlH 4 , prepared by ball milling, are studied for the first time. The hydrogen storage properties and reaction mechanism are investigated by pressure−composition−temperature (PCT), differential scanning calorimetry (DSC), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The nonisothermal desorption results show that MgH 2 −LiAlH 4 + 5 mol % MnFe 2 O 4 has a lower onset dehydrogenation temperature, 85, 50, and 40°C lower than these of ball-milled MgH 2 −LiAlH 4 sample for each stage in the dehydrogenation process. The isothermal dehydriding kinetics and isothermal rehydrogenation kinetics results indicate that adding MnFe 2 O 4 to MgH 2 −LiAlH 4 could significantly enhance the absorption/desorption kinetics of MgH 2 −LiAlH 4 . From the differential scanning calorimetry and Kissinger analysis, the apparent activation energy of the 5 mol % MnFe 2 O 4 -doped sample for the three decomposition stage is 55.8, 70.8, and 96.5 kJ/mol, resulting in a 45.7, 85.5, and 99.6 kJ/mol decrease, respectively, compared with the MgH 2 −LiAlH 4 sample. These improvements are mainly attributed to in situ formed Fe 0.872 O phase and the amorphous Mn-containing phase during the dehydrogenation process, which act as the real catalyst in the MgH 2 −LiAlH 4 + 5 mol % MnFe 2 O 4 composite.