A novel Diels-Alder polymerization system was developed, using an azodicarbonyl compound as the dienophile. A bis(azodicarbonyl) monomer was prepared by quantitative oxidation of bis(diacylhydrazine) with (BuOCl)-Bu-t in the presence of pyridine. Diels-Alder polymerization was carried out with a bisdiene monomer, using AgOTf as the catalyst. High thermal stability of the polymer is characteristic for the products of this Diels-Alder polymerization system, in which the Diels-Alder reaction is irreversible. The C=C bond in the Diels-Alder polymer can be cleaved by ozonolysis to give a polyketone.