High molecular weight poly (ether sulfonamide) has been prepared by condensation of 4,4＇-dichlorosulfonyldiphenylether with ethylenediamine. The reaction of potassium salt of poly (ether sulfonamide) with epichlorohydrin gives the corresponding N-glycidiyl derivative in yield as high as 98%. The resulting polymer offers many functionalization possibilities through ring opening of the oxirane units.Also the glycidiyl bearing polymer may act as muitifunctional post-crosslinking agent for polymers carrying hydroxy, amino or carboxyl groups.