The catalytic effects of MnFe2O4 nanoparticles on the dehydrogenation properties of MgH2, prepared by ball milling, are investigated for the first time. The onset dehydrogenation temperature for MgH2 + 7 mol % MnFe2O4 is 300 degrees C, 140 degrees C lower, compared with the as-received MgH2. The isothermal dehydriding kinetics shows that 7 mol% MnFe2O4-doped sample can release 5.05 wt.% hydrogen in 1 h at 300 degrees C under 0.1 MPa pressure, whereas as-received MgH2 releases only 0.49 wt.% hydrogen for the same conditions, indicating significantly improved dehydrogenation. From the differential scanning calorimetry and the Kissinger desorption kinetics analysis, the apparent activation energy of 7 mol% MnFe2O4-doped sample is 64.55 kJ mol(-1), resulting in 190.34 kJ mol(-1) decrease, compared with the as-received MgH2, which is lower than that of MgH2 doped with other reported transition metal oxide catalysts. Based on X-ray diffraction and X-ray photoelectron spectroscopy tests, Mg2MnO4 and Fe0.872O phases together play a synergistic role in remarkably improving MgH2 dehydriding properties. (C) 2013 Elsevier B.V. All rights reserved.