Abstract Gamma ray-induced bulk polymerization of 1,3,5,7-tetravinyltetramethylcyclotetrasiloxane at ambient temperature has been investigated. It was found that the polymerization proceeds via a free radical mechanism through the reaction of vinyl groups, and the resulting polymer had a three-dimensional network structure. Kinetic features of the reaction were also studied, strong postpolymerization effects were observed at doses between 8 and 80 kGy. The composition of the sol fractions was determined by high pressure liquid chromatography, and the chemical structure of both the sol and gel fractions was analyzed by FTIR spectroscopy. Thermal stability of the gel fractions, determined by thermogravimetric analysis, and the thermomechanical behavior of unextracted samples were found to depend on the irradiation dose.