Nylon3 (poly-beta-alanine) gamma irradiated in nitrogen was investigated by Electron Spin Resonance Spectroscopy to elucidate the type of radicals generated, their relative abundance, conversion into other radicalic species and their room temperature stability. Two types of radiation induced primary radicals have been detected. One of them (R-1) occurs by hydrogen abstraction from methylene group next to the carbonyl group, while the other (R-2) by hydrogen abstraction from methylene group next to amide group. R1 is observed to be converted into an alkoxy radical (R-3). Decay kinetics of the radicals in nitrogen was also examined and decay mechanisms have been proposed for each radical. (C) 2012 Elsevier Ltd. All rights reserved.