This article first reports a fast and controlled living radical polymerization (LRP) of acrylonitrile, evidenced by 81.3% monomer conversion within 40 min and well-defined the polymers with a narrow polydispersity index (PDI) range of 1.14-1.38. This was achieved by utilizing azobis(isobutyronitrile) as radical initiator with a high concentration up to 190 mM and CuBr2 as catalyst with a very low concentration down to 50 ppm. The polymerization displayed typical LRP characteristics, including pseudo first-order kinetics of polymerization, the linear increase of number-average molecular weights (MWs), low PDI values. The influence of various experimental components, radical initiator concentration, catalyst concentration, and reaction temperature, on the polymerization reaction and MW as well as PDI has been investigated in detail. 1H NMR and gel permeation chromatography analyses as well as chain extension reaction confirmed the very high chain-end functionality of the resultant polymer. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012