The quality of EVA copolymers (ethylene and vinyl acetate copolymers) depends on the impurities in the feed. The removal of acetic acid, formed due to the partial degradation of the EVA copolymer, by adsorption from the recycle ethylene stream has been studied. Activated carbon proved to be useful for this purpose due to its high adsorption capacity and selectivity to acetic acid and its easy and complete regeneration. Adsorption isotherms and breakthrough curves of ethylene, acetic acid, and vinyl acetate, and binary acetic acid-vinyl acetate mixtures have been obtained at 293 K, Mass transfer and pore diffusion coefficients have been determined using two adsorption models. These data have allowed the design of an adsorption installation for the improvement of quality of EVA copolymer.