A corrosion inhibiting compound with a general structure A-B or A-X-B for inhibition of corrosion of steel in acidic solution. A comprises a heterocyclic ring system having a plurality of cyclic Carbon atoms and at least one cyclic Nitrogen atom, wherein the at least one cyclic Nitrogen atom is neutral under neutral conditions and protonatable under acidic conditions. B comprises at least two unsaturated Carbon atoms. B may comprise a ring system or a polymerisable group.