A corrosion inhibiting composition which is a liquid carrier in which is dissolved or dispersed a corrosion inhibitor compound comprising at least one moiety (A) which is an aliphatic, aromatic or mixed aliphatic/aromatic structure containing one or more hetero atoms which are nitrogen, oxygen, phosphorus or sulphur, and also at least one moiety (B) which contains one or more polymerisable groups containing double or triple bonded carbon, with the moieties (A) and (B) directly or indirectly covalently connected together.