Abstract The kinetics of unimolecular spontaneous and bimolecular amine induced decomposition of dibenzoyl peroxide (DBP) in partially restricted polymer media was studied. Initial reaction rates were calculated and used for evaluation of kinetic parameters. Activation energies were calculated: for spontaneous decomposition of DBP, the activation energy increases with increasing viscosity but for amine-induced decomposition the activation energy decreases as the viscosity increases, attributed to increase of the stability constant for the intermediate charge transfer complex. The rate constants were deduced under iso-viscous conditions at various temperatures. The iso-viscous values of rate constants were used to evaluate the activation parameters.