series of new reversible addition-fragmentation chain transfer (RAFT) agents with cyanobenzyl R groups were synthesized. In comparison with other dithioester RAFT agents, these new RAFT agents were odorless or low-odor, and this made them much easier to handle. The kinetics of methyl methacrylate radical polymerizations mediated by these RAFT agents were investigated. The polymerizations proceeded in a controlled way, the first-order kinetics evolved in a linear fashion with time, the molecular weights increased linearly with the conversions, and the polydispersities were very narrow (similar to 1.1). A poly[(methyl methaerylate)-block-polystyrene] block copolymer was prepared (number-average molecular weight = 42,600, polydispersity index = 1.21) from a poly(methyl methaerylate) macro-RAFT agent. These new RAFT agents also showed excellent control over the radical polymerization of styrenics and acrylates. (c) 2005 Wiley Periodicals, Inc.