A novel diisocyanate containing flexible oxyethylene moieties and preformed imide rings was synthesized. The diisocyanate was prepared from the parent diacid and a subsequent Curtius rearrangement of the corresponding diacylazide. The polycondensation reaction of the diisocyanate with different dianhydrides resulted in the prepara tion of three polyimides with good solubility and thermal stability, The monomer and polymers were fully characterized. and me physical properties of the polymers were studied.