The separation of water-oil emulsion with cellulose membranes modified with a unipolar corona discharge at voltage of 5–25 kV and time of 1–5 min was investigated. The results of the X-ray diffraction analysis and of the electrostatic field parameters measurements showed a decrease in crystallinity from 0.29 to 0.27 and the formation of positive charges on the surface of the sample, while the formation of a double electric layer according to dielectric spectrometry data was not detected. During the separation of the model water-oil emulsions, an increase in efficiency was revealed as 80% to 98% and the separation productivity from 15 dm³/(m²·h) to 35 dm³/(m²·h) after treatment in the field of a unipolar corona discharge of cellulose acetate membranes, which is explained by a change in the supramolecular and chemical structure of the latter.