Abstarct: The aim of this study was to synthesize 4-(4-methoxybenzylideneamino)-1,2,4-triazolidine-3,5-dione via the reaction of 4-methoxybenzaldehyde with one mole of urazine in ethanol as solvent. We also prepared 4-phthalimido-1,2,4-triazolidine-3,5-dione via the of reaction phthalic anhydride with one mole of urazine in DMAc. The structures of the monomers were identified and confirmed with the help of IR and 1HNMR spectroscopy. The polymerization of the monomers with equal moles of various diisocyanates, hexamethylene diisocyanate (HMDI), tolylene diisocyanate (TDI), and isophorane diisocyanate (IPDI), led to new polymers, in high yields and inherent viscosities. The characterization of the monomers was achieved using IR and 1HNMR spectroscopies, viscometery and thermal gravimetric analysis (TGA/DTG).