Liquid-liquid equilibria (LLE) data for the quaternary system water + acrylic acid + acetic acid + cyclohexane at (293.15, 303.15, and 313.15) K have been measured at atmospheric pressure. The reliability of the experimental LLE data was ascertained through Othmer-Tobias and Bachman correlations. The pseudoternary phase diagrams at different temperatures for the quaternary system were given. The nonrandom two-liquid (NRTL) and universal quasichemical activity coefficient (UNIQUAC) models were used to correlate the data of the quaternary system. The calculated values from both models agree well with the experimental values.