AbstractMechanical milling (MM) is an useful technique to improve the H-kinetics of magnesium hydride (MgH2) by crystallite and particle size reduction. In the present work, we report the significant influence of impurities coming from the milling tools on magnesium H-sorption properties. We have observed that a high impurity level leads to powder agglomeration and subsequently, it prevents an efficient reduction of MgH2 particle size. Therefore, a drawback in H-sorption properties is observed. Finally, a short outlook about the influence of impurities on desorption temperature of MgH2 milled with different additives (metal-oxides) will be presented.