The Mg

2

Ni

0.9

Co

0.1

hydrogen storage alloy was prepared by metallurgical method

and the phase composition and microstructure of the alloy were invesiagted by XRD and SEM/EDS

meanwhile the hydrogen absorption and desorption properties of the alloy were anlyzed by PCT and DSC. The results reveal that the as-cast alloy is composed of peritectic Mg

2

Ni phase

Mg-Mg

2

Ni eutectic structure and a small amount of the first precipitated Mg-Ni-Co ternary phase.The element Co can be dissolved in the Mg

2

Ni phase to form a Mg

2

（Ni

Co）solid solution phase. The alloy is transformed into Mg

2

NiH

4

phase

Mg

2

Ni

0.9

Co

0.1

H

4

phase and MgH

2

phase after hydrogen absorption. The partial substitution of Co for Ni in the Mg

2

Ni significantly improves the isothermal de-/hydrogenationkinetic properties of the alloy

and the hydrogen release temperature of Mg

2

Ni

0.9

Co

0.1

hydride is significantly reduced. The initial hydrogen release temperature is about 200 ℃.