The present invention discloses a hydrogen storage medium including a composite of an alloy and a catalyst/expandable graphite. The expandable graphite can be replaced by activated carbon. The catalyst content is 1-50% based on the weight of the medium, which can be Pd, Pt, Cu, Co or Ni. The alloy can be a Mg-based alloy, Ti-based alloy, La-based alloy, Mn-based alloy or Fe-based alloy. The present invention also discloses a process for preparing a hydrogen storage composite.