A procedure was developed for benzoylating the polystyrene segments in polystyrene-b-poly(ethylene-co-butene)-b-polystyrene (SEBS) triblock copolymers. The products were characterized by NMR spectroscopy, gel permeation chromatography, dynamic mechanical thermal analysis, and membrane osmometry. The mechanical properties of the parent and benzoylated copolymers, measured from 25 to 150degreesC, indicated that benzoylation increases the utility of the polymers at elevated temperatures.