Abstract: Apparatus for the storage of hydrogen comprising a fibrous encapsulating material and solid particles of an intermetallic compound capable of reversibly absorbing hydrogen encapsulated in the material, the material being porous to the ingress and egress of hydrogen, but being impervious to the solid particles of the intermetallic compound, and a cylindrical gas tight heat exchange chamber, including an inlet and outlet, enclosing the encapsulated intermetallic compound, the porous, fibrous material being of generally strip form and being spirally wound to form a generally cylindrical body which is housed within the gas tight chamber.