Liquid-liquid equilibria for the ternary system water + acetic acid + 2-pentanol over the temperature range 288-323 K were used to estimate the interaction parameters between each of the three compounds for the NRTL and UNIQUAC equations, and between each of the main groups of H 2 O, CH 2 (paraffinic CH 2 ), OH and COOH for the UNIFAC equation as a function of temperature. The NRTL model gave the lowest errors in correlating the overall equilibrium compositions of the studied system.