The Co-60-gamma rays radiation-induced and free radical-initiated copolymerizations of allyl glycidyl ether with styrene were studied comparatively. The latter was carried out at 60 degrees C for 1, 3, 5 and 7 days using azobis(isobutyronitrile) as a radical initiator, while in the first one the samples were irradiated at the different absorbed doses of 55, 110 and 165 kGy. Changes in chemical structure during copolymerization in both methods were analyzed by using proton nuclear magnetic resonance spectroscopy (1H NMR) and Fourier transform infrared spectroscopy. Thermal properties of the products were examined by means of thermogravimetry. Thermal stability values of poly(allyl glycidyl ether-co-styrene) (poly(AGE-co-St)) samples obtained by radical polymerization were quite similar to those of samples obtained by irradiation. The molecular weights (M-w and M-n) of the copolymers were determined by using gel permeation chromatography. The results showed that the polymerization method affects the polydispersity index of the copolymers. The results indicated that the radiation-induced copolymerization had a lower yield than that of radical initiator copolymerization.