In the present work, spectroscopic, kinetic and dosimetric features of the radicalic intermediates produced after gamma irradiation at room temperature of solid triclosan (2,4,4-trichloro-2-hydroxydiphenyl ether; TCS) were investigated by means of electron spin resonance spectroscopy (ESR) at various temperatures. The same material was also irradiated with UV light, and an ESR spectrum very similar to that obtained for gamma-irradiated TCS, was recorded. The ESR spectrum of TCS is characterized by an unresolved doublet with resonance lines split into other doublets. An evaluation technique based on variations of four assigned peak-to-peak amplitudes and signal intensity was adopted, to monitor the evolution of the spectrum under different experimental conditions. Radicals of one type were proposed to be created upon irradiation exhibiting decays via intra-track and inter-track recombination reactions with activation energies of 43 +/- A 2 and 139 +/- A 6 kJ/mol, respectively. A radical exhibiting axial g anisotropy and interacting with two un-equivalent protons was found to describe the experimental spectrum well. The sensitivity of TCS to gamma radiation was high (G = 0.12) suggesting TCS to be a suitable dosimetric material in measuring normal and accidental radiation doses in the range of (1-25 kGy).