This study aims to investigate the efficiency of dimethyl phthalate (DMP), having low water Solubility, low density, and a high boiling point compared to alkalies, as a solvent to extract toluene from its multicomponent hydrocarbon mixtures. Liquid-liquid equilibrium (LLE) data of the Solubility (binodal) curves and tie-line end compositions were examined for mixtures of (heptane or hexane or cyclohexane (1) + toluene (2) + DMP (3)) Lit T = 298.15 K and 101.3 kPa. The reliability of the experimental tie-line data was verified by using the Othmer-Tobias correlation. Distribution coefficients and separation factors were evaluated for the immiscibility region. The experimental tie-line data were correlated by the universal quasichemical activity coefficient (UNIQUAC) equation and also predicted with the universal functional group activity coefficient (UNIFAC) model. The experimental data were compared with the calculated results.