A device for the storage of compressed hydrogen gas comprises a plurality of glass capillary tubes each having a sealed extremity and an open extremity, wherein said plurality of glass capillary tubes is sheathed in an external tubular cover, and wherein the open end of a bundle of said tubular covers is housed in an adaptor, and wherein said adaptor is suitable to allow compressed hydrogen gas to be added to, and to prevent said hydrogen gas from escaping from, said glass capillary tubes.