In the present embodiment, bisphthalonitrile resin has been cured using synthesized novel bisphenyl nitrile-containing benzoxazine (NBZ) vis-a-vis traditional curing agents such as 4-(3'aminophenoxy)diphenyl sulphone (m-DDS) and amino-functionalized phthalonitrile (APN) to study the curing efficacy coupled with processing window and mechanism of curing. It has been established by FT-IR and DSC that NBZ molecules cure the bisphthalonitrile resin matrix by formation of free phenolic groups which act as nucleophile triggering the curing reaction through nitrile-nitrile addition polymerization reaction. Additionally, it has been seen that NBZ-catalyzed phthalonitrile resin curing system showed better processing window in comparison to m-DDS- and APN-catalyzed system. Considering the end-user applications, the NBZ- and m-DDS-cured resins have also been studied for their TG, DMA, water uptake, thermo-oxidative and dielectric properties.