A new catalytic system, FeCl3/isophthalic acid, was successfully used in the reverse atom transfer radical polymerization (RATRP) of methyl methacrylate (MMA) in the presence of a conventional radical initiator, 2,2'-azo-bis-isobutyrontrile. Well-defined poly(methyl methacrylate) (PMMA) was synthesized in an N,N-dimethylformamide solvent at 90-120 degreesC. The polymerization was controlled up to a molecular weight of 50,000, and the polydispersity index was 1.4. Chain extension was performed to confirm the living nature of the polymer. The kinetics of the RATRP of MMA with FeCl3/isophthalic acid as the catalyst system was investigated. The apparent activation energy was 10.47 kcal/mol. The presence of the end chloride atom on the resulting PMMA was demonstrated by H-1 NMR spectroscopy. (C) 2001 John Wiley & Sons, Inc.