In this paper, the possibility for determination of the tritiated water activity using Electron Paramagnetic Resonance (EPR) spectrometry was analyzed. The method relies on estimation of hydroxyl radicals resulted from self-radiolytical processes using EPR spectrometers. The mechanisms of inducing of free radical by self radiolysis of tritiated water, the accumulation time of hydroxyl radicals and the corroboration of signals amplitude with the tritiated water concentration have been studied.