In this study, for acetic acid dehydration by the pervaporation method, poly(2,6-dimethyl-1,4-phenylene oxide) composite membranes have been synthesized with the introduction of a modifier of a new type, which is a representative of the class of deep eutectic solvents and based on zinc chloride and acetamide taken in a molar ratio of 1 : 3. The membrane structure has been studied by scanning electron microscopy and X-ray diffraction analysis; thermal stability has been determined by thermogravimetric analysis. Transport properties have been studied by vacuum pervaporation during the separation of a water-acetic acid mixture. It has been shown that the introduction of a deep eutectic solvent contributes to an increase in the membrane flux and selectivity in the case of a small amount of the modifier. The highest separation factor has been found for a membrane containing 5 wt % of the modifier (more than 99 wt % of water in the permeate).