Solubility and liquid-liquid equilibrium (LLE) for the quaternary system acetic acid-n-propanol-n-propyl acetate-water and for the ternary sub-systems acetic acid-n-propyl acetate-water and n-propanol-n-propyl acetate-water were studied at 293.15 K and 303.15 K and atmospheric pressure. Binodal surfaces and curves, tie-lines, and compositions of critical LLE points were determined. Experimental LLE data were correlated by UNIFAC and NRTL models. (C) 2014 Elsevier B.V. All rights reserved.