The present invention relates to a bung closure (10) for the gas-tight and liquid-tight closure of the bung opening of a container, in particular of a steel barrel for storing and for transporting in particular hazardous fluid contents. The bung closure (10) consists substantially of a cup-like basic body (12) made of metal. The basic body has a disc-like base (14) and an upwardly open tubular ring part (16) adjoining the same, wherein at least the outside of the ring part (16) has applied to it a plastic layer (18) and a corresponding thread (20) is formed for the purpose of screwing the bung closure (10) into the bung opening of the steel barrel.