ABSTRACT This study was based on preparation of a new category of polyurethanes with improved glass transition temperature. Firstly, diphenylsilanediol was reacted with methylene diphenyl diisocyanate and also toluene diisocyanate in 2:1 stoichiometric ratio to prepare two different urethane diols. Then, polycondensation reactions of the obtained diols with 4,4′-dichlorodiphenyl sulfone resulted in preparation of novel poly(silyl ether-sulfone-urethane)s. Spectroscopic techniques and elemental analysis were used to wholly characterize the chemical structure of the monomers and the resulting polymers. Viscosity, solubility, thermal behavior and stability, and crystallinity of the polymers were studied and through that, structure-property relationship of the two polymers was investigated. The prepared poly(silyl ether-sulfone-urethane)s had improved glass transition temperature in comparison to conventional polyurethanes with Tg of 143–165°C. The resulted polymer from methylene diphenyl diisocyanate showed higher glass transition temperature but lower solubility (average solubility in polar solvents was 3.7 vs. 4.0 g/dL) than polymer derived from toluene diisocyanate.