The seal (1) is adapted to be heat bonded to a container for closing an opening of the container. Said seal (1) is a laminate comprising a metallic layer (10), a liner (12) that is permeable to water vapour and to molecular hydrogen, and that can be heat bonded to a container, and at least an active layer (11), that is positioned between the metallic layer (10) and the liner (12), and that is capable of chemically reacting with water and generating molecular hydrogen.