Norbornadiene was polymerized, in moderate yield by MoCl5 or EtAlCl(2). By using both components together, an increase in reaction rates and in polymer yields were observed. By the optimization of the reaction conditions, 100% of polymer yield was achieved. For comparison, the polymerization of the NBD was also accomplished by using initiators such as AlCl3, Et(3)Al, AZBN, and n-butyl lithium. All the obtained polymers gave similar IR and NMR spectra indicating the presence of the polynortricyclene structures. Though they show different molecular weight distribution, the solubilities of the polymers (obtained using MoCl5, AlCl3, EtAlCl(2), and MoCl5/EtAlCl(2)) are very similar. DTA analyses show that the polymers (obtained by using MoCl5/EtAlCl(2) pair or n-butyl lithium or Et(3)Al) have high thermal stabilities whereas all the other polymers are unstable in air.