Iron(II) chloride coordinated by succinic acid was first used as the catalyst in 2-chloropropionitrile-initiated atom transfer radical polymerization (ATRP) of acrylonitrile. N,N-dimethylformamide was used as a solvent to improve the solubility of the ligand. An iron(II) chloride to succinic acid ratio of 0.5 not only gives the best control of molecular weight and its distribution but also provides rather rapid reaction rate. Effects of solvent on polymerization of acrylonitrile were also investigated. The induction period is shorter in N,N-dimethylformamide than in propylene carbonate and toluene and the rate of the polymerization in N,N-dimethylformamide is fastest. The molecular weight of polyacrylonitrile agrees reasonably well with the theoretical molecular weight of N,N-dimethylformamide. The rate of polymerization increases and the induction period becomes shorter with increasing polymerization temperature, and the apparent activation energy was calculated to be 56.5 kJ mol(-1). (c) 2005 Wiley Periodicals, Inc.