The dependence of the rate constant of free-radical decay on pressure in γ-irradiated polycarbonate has been studied in the temperature range between 90°C and 200°C at up to 800 MPa on the basis of the changes in ESR spectra. The results are compared with data about mechanical relaxations which provide information on molecular motions. The correlation between molecular motions in the α-relaxation region and radical decay is painted out.