Abstract: This invention relates to a composition which may be used in particular for manufacturing stoppers and to a process for manufacturing same.A composition is principally constituted by particles of ligneous plant matters such as natural cork or wood, by a plastics material of closed cellular structure such as expansible microspheres, and by a binding agent; a stopper comprises at least one active part constituted by a composition according to the invention, and said binding agent is a glue suitable for contact with foodstuffs, for example of the polyurethane or acrylic type.The technical domain of the invention is that of the cork industry.