Experimental (liquid + liquid) equilibrium data for the mixtures of (heptane, or hexane, or cyclohexane + toluene + 1,3-dimethyl-2-imidazolidinone) were determined at T = 298.15 K and P = 101.3 kPa. The Solubility (binodal) curves and tie-line end compositions are reported for the related mixtures and presented as complete phase diagrams. Distribution coefficients and separation factors were evaluated for the immiscibility region. The reliability of the experimental tie-line results was verified by using the Othmer-Tobias correlation. The experimental tie-line data were correlated by UNIQUAC model, which gave satisfactory representation for the systems, It was observed that the separation of toluene from cyclohexane is easier to achieve than from heptane and hexane. (C) 2009 Elsevier Ltd. All rights reserved.