Abstract The Co 60 γ-ray radiation induced polymerization of butadiene in bulk and in ethanol at temperatures ranging from 15 to 45°C was studied. Hydrogen peroxide was used as initiator on some occasions. The mechanism of the polymerization in ethanol seems to be fitted to the no energy transfer kinetics as described by Chapiro (1962). The ratio of relative rate of free radical production of solvent/monomer φ rel is 19. When hydrogen peroxide was added, the polymerization rate increased and hydroxyl terminated polybutadiene was obtained. The microstructure of polybutadiene was studied by i.r. and NMR spectra.