A Mg-30 wt% TiMn 1 . 5 hydrogen storage composite was successfully synthesized by mechanical milling of a mixture of magnesium powder and amorphous TiMn 1 . 5 powder. The absorption/desorption rates and storage capacity under different temperatures were evaluated. The composite possesses high hydrogen storage capacity and exhibits excellent absorption/desorption kinetic properties and is activated in situ due to reaction ball milling (RBM). The hydrogen capacity is over 2.7 wt% at 373 K, and one absorption/desorption hydrogen cycle can be finished in 20 min at 523-573 K. Interestingly, the desorption temperature begins at about 500 K, decreasing about 40 K in contrast to that of the milled pure MgH 2 . Mechanical milling produces fine powder with nanometer-scaled grains and introduces many imperfections into the Mg matrix, which contribute to the enhanced hydrogen absorption/desorption rates with high capacity catalyzed by TiMn 1 . 5 (amorphous).