A novel reversible addition-fragmentation chain transfer (RAFT) agent, S,S-bis(2-hydroxylethyl-2'-butyrate)trithiocarbonate (BHEBT), was first successfully synthesized in the presence of an anion-exchange resin with OH- form, and then it was used as chain transfer agent in RAFT polymerizations of styrene or methyl acrylate, the dihydroxyl-terminated polymers with controlled molecular weights and narrow molecular weight distributions were produced, which was confirmed by GPC, H-1 NMR spectra and kinetic analysis. Furthermore, these obtained telechelic polymers with trithiocarbonate group in the middle of the chains were used as macro chain transfer agents in the further RAFT polymerizations, and well-defined telechelic dihydroxyl-terminated triblock copolymers have been prepared successively. The structures were confirmed by their IR and H-1 NMR spectra. (C) 2004 Elsevier Ltd. All rights reserved.