Abstarct: 4-Phenylurazole was reacted with two moles of 2-bromoethanol in DMAc as solvent, at room temperature to produce 1,2-bis(2-hydroxyethyl)-4-phenyl-1,2,4-triazolidine-3,5-dione. The structure of the product was determined by IR, 1H-NMR and 13C-NMR spectra. This compound which is a new monomer was then reacted with two moles of phenyl isocyanate and the structure of product as a model compound was identitied. The structure of the model compound was determined by IR, 1H- NMR spectra. The polymerization of the monomer with equal moles of various diisocyanates, hexamethylene diisocyanate (HMDI), tolylene diisocyanate (TDI), and isophorane diisocyanate (IPDI), led to new polyurethanes, with high yields and inherent viscosities. The structures of these polyurethanes were confirmed using infrared spectroscopy, viscometery and thermal gravimetric analysis (TGA/DTG).