  Magnesium hydride (MgH2) is the mostly used material for solid-state hydrogen
storage. However, their slow kinetics and highly unfavorable thermodynamics
make them unsuitable for the practical applications. The current study
describes the unusual catalytic action of a new class of catalyst, a
high-entropy alloy (HEA) of Al20Cr16Mn16Fe16Co16Ni16, on the
de/re-hydrogenation properties of MgH2. The onset desorption temperature of
MgH2 is reduced significantly from 376 {\deg}C (for pristine MgH2) to 338 degC
when it is catalyzed with a HEA-based catalyst. On the other hand, a fast
de/re-hydrogenation kinetics of MgH2 was observed during the addition of
HEA-based catalyst. It ab sorbs 6.1 wt% of hydrogen in just 2 minutes at a
temperature of 300 degC under 10 atm hydrogen pressure and desorbs ~ 5.4 wt%
within 40 minutes. At moderate temperatures and low pressure, the HEA-based
catalyst reduced desorption temperatures and improved re-hydrogenation
kinetics. Even after 25 cycles of de/re-hydrogenation, the storage capacity of
MgH2 catalyzed with the leached version of HEA degrades negligibly.
