We report herein that copolymers containing glycidyl methacrylate (GMA) with acrylonitrile (AN) units were synthesized by free radical solution polymerization technique using benzoyl peroxide as a free radical initiator and 1,4‐dioxane as a solvent at 70°C. The copolymerization behavior was studied in different composition with the mole fractions of GMA ranging from 0.20 to 0.80 in the feed and under 10% copolymer conversion. The copolymers were characterized by Fourier transform infrared spectroscopy, gel permeation chromatography, and scanning electron microscopy techniques. The thermogravimetric analysis of the copolymers suggest an overall decrease in the thermal stability of the copolymer with decreasing content of GMA in the copolymers. Thermal decomposition activation energies are calculated by the Ozawa method. The copolymer composition was determined by the application of elemental analysis method. The monomer reactivity ratios were estimated by the application of conventional linearization methods, such as Kelen–Tudos (K‐T), Fineman–Ross (F‐R) methods, and a nonlinear error in variable model (RREVM) method using a computer program, and all results were discussed and compared with the literature.