Curing process of an amine-epoxy system was investigated using vibrating reed technique and torsion pendulum apparatus, working at frequencies of about 100Hz and 1Hz, respectively. The measurements of mechanical spectra were carried out in isothermal conditions (300–325K) at different frequencies in time domain i.e. in the course of chemical reaction between epoxy resin and a hardener. It was shown that the curing reaction is observed as an asymmetrical maximum of Q−1(t) which position is correlated with the inflection point of free vibrations frequency f(t) curve. An increase of the measurement temperature and frequency causes a shift of the observed mechanical spectra into shorter times.