Abstract: The invention relates to N-bridged polynitrons and their use for cross-linking of unsaturated polymers, as well as a curable composition comprising (a) a N-bridged polynitron, (b) an unsaturated polymer or a mixture of polymers, wherein at least one unsaturated polymer contains unsaturated functions or functional groups which can react with the polynitron, (c) optionally fillers, (d) optionally pigments, (e) optionally additives such as plasticizers, stabilizers, photoinitiators, and (f) optionally, other cross-linking agents such as polyisocyanates, bisdienes, polyoxaziridines, and their use as adhesives, rubber, filling, sprayable thick-layer filler, ink, paint, powder paint, waterborne paint or solvent based paint. Further, the invention relates to cross-linking products obtainable by curing the curable composition according to the present invention.