N36 zirconium ally was developed by NPIC as a fuel rod cladding and other component materials for the use in nuclear reactor cores.The lead test rods of N36 cladding which was fabricated using low-deformation process(LDP)had been irradiated in commercial reactor.Since that,the fabrication process of N36 was optimized by the use of a high-deformation process(HDP).The lead test assemblies of LDP and HDP N36 cladding are being irradiated in the same commercial reactor.Out-of-pile and in-reactor performance of N36 cladding is reviewed in this paper with a primary emphasis on LDP N36 cladding.After the 2nd cycle irradiation which achieved an intermediate burn up in the range of 20-28 GWd/MTU,the lead test rods showed excellent in-pile properties.