Several difficulties are reported in literature about the experimental analysis of polymerizations involving 2-hydroxyethyl acrylate (HEA), mainly due to transfer reactions that characterize the system. In particular, major problems are emerged in the study of free radical copolymerization kinetics of HEA. In this work, free-radical copolymerization propagation kinetics of HEA and styrene (ST) are investigated through a computational approach based on density functional theory. Monomer reactivity ratios for HEA/ST copolymerization are calculated at 50 degrees C and 125 degrees C, obtaining values that exhibit a weak dependence on temperature. In particular, HEA reactivity ratio, r(HEA), equal to 0.14 and ST reactivity ratio, r(ST), equal to 0.31 at 50 degrees C, whereas r(HEA) = 0.17 and r(ST) = 0.29 at 125 degrees C. Moreover, the reliability of such parameters has been tested by analyzing copolymer composition data as a function of monomer feed composition, at the same temperatures indicated above. Experimental values proposed in literature are well predicted by the terminal copolymerization model using the kinetic parameters computationally determined. POLYM. ENG. SCI., 51:2109-2114, 2011. (C) 2011 Society of Plastics Engineers