A new hyperbranched aromatic poly(ether sulfone) with sulfonyl chloride terminal groups was prepared by polycondensation of a new AB(2) monomer (1), 4,4'-(m-phenylenedioxy)bis(benzenesulfonyl chloride). The polymerization was carried out in nitrobenzene at 120 degrees C for 3 h in the presence of a catalytic amount of FeCl3, giving the polymer with number-average molecular weights up to 35,700. Furthermore, an ABA block copolymer was prepared from a linear polymer, poly(ether sulfone) with sulfonyl chlorides at both ends and AB(2) monomer 1.