FeCl3 coordinated by isophthalic acid was first used as a catalyst in the azobisisobutyronitrile-initiated reverse atom transfer radical polymerization of acrylonitrile. N,N-Dimethylformamide was used as a solvent to improve the solubility of the ligand. An FeCl3-to-isophthalic acid ratio of 0.5 not only gave the best control of the molecular weight and its distribution but also provided rather a rapid reaction rate. The effects of different solvents on the polymerization of acrylonitrile were also investigated. The rate of the polymerization in N,N-dimethylformamide was faster than that in propylene carbonate and toluene. The molecular weight of polyacrylonitrile agreed reasonably well with the theoretical molecular weight in N,N-dimethylformamide. The rate of polymerization increased with increasing polymerization temperature, and the apparent activation energy was calculated to be 59.9 kJ mol(-1). Reverse atom transfer radical polymerization was first used to successfully synthesize acrylonitrile polymers with a molecular weight higher than 80,000 and a narrow polydispersity as low as 1.22. (c) 2005 Wiley Periodicals, Inc.