Abstract: The esterifications of hydroxy-terminated liquid polymers, such as liquid tetrahydrofuran-propylene oxide copolymer,with maleic anhydride were investigated and carboxyl-vinylene-terminated liquid copolymers were obtained. Under certain conditions,such as reaction temperature,feed ratio and with suitable catalysts, 100% conversion of terminal groups has been achieved. The degree of terminal group conversion and the structure of the po-lymers were determined by chemical titration,IR and ¹H-NMR, respectvely.