Maleimide and 2-aminobenzonitrile (MIan)-based benzoxazine has been synthesized and characterized. MIan contains imide, oxazine, and nitrile functional groups that can react almost simultaneously, leading to complicated reaction mechanisms. For understanding the fundamental polymerization mechanism, the model benzoxazine compound is synthesized. The ortho-nitrile group in the model compound undergoes cyclization reaction, producing the thermally stable six-membered ring species resulting in the excellent thermal properties of the material. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 2559-2565, 2010