A radiation curable composition comprising a curable compound, a photo-initiator and a co-initiator, wherein said co-initiator has a structure according to Formula I A-L-B  Formula I wherein A represents a structural moiety comprising an aromatic tertiary amine; B represents a structural moiety comprising at least one aliphatic tertiary amine; L represents a divalent linking group positioning the nitrogen atom of the aromatic amine of the structural moiety A and the nitrogen of at least one aliphatic amine of the structural moiety B in a 1-3 to 1-23 position; with the proviso that at least one aromatic and at least one aliphatic amine each have at least one alfa-hydrogen.