The Mg2NiH4 complex hydrides were synthesized by high-energy ball milling (HEBM) MgH2 + Ni mixtures. Multi-walled carbon nanotubes (MWCNTs) or TiF3 as catalysts were added and the catalytic-dehydrogenation behaviors were investigated. All prepared samples are characterized by X-ray diffraction (XRD) spectroscopy, scanning electron microscope (SEM) and differential scanning calorimetry (DSC) to acquire information of microstructure, phase compositions, surface and dehydrogenation properties. The results indicate that the method of adding catalysts by HEBM is reasonable and the hydrogen desorption property of Mg2NiH4 is improved by catalysts. It is worth noting that the dehydrogenation temperature (T-D) and the activation energy (E-a) of Mg2NiH4 catalyzed by MWCNTs coupling with TiF3 are reduced to 230 degrees C (243.6 degrees C of Mg2NiH4) and 53.24 kJ/mol (90.13 kJ/mol of Mg2NiH4), respectively. The addition of proper catalysts is proved to be an effective strategy to decrease T-D and E-a of Mg2NiH4 hydrides. Copyright 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.