Solubility, critical states and liquid-liquid equilibrium (LLE) data for the quaternary system acetic acid-ethanol-ethyl acetate-water and for the ternary sub-systems acetic acid-ethyl acetate-water and ethanol-ethyl acetate-water were obtained at 293.15K and atmospheric pressure. Binodal curves, tielines and compositions of critical points were determined. In order to construct the binodal surface and critical curve of the quaternary system, three quaternary sectional planes with several ratios of acetic acid and ethanol were studied. Experimental LLE data were compared with the values calculated by UNIFAC model and it was found that the experimental and calculated data are in a good agreement. (C) 2011 Elsevier B.V. All rights reserved.