Densities of the ternary mixtures chlorobenzene + n-hexane + (n-undecane or n-dodecane) have been measured at 298.15 K and atmospheric pressure. The excess molar volumes were computed from the experimental data and were fitted to the Nagata equation. The partial excess molar volumes were calculated, an interpretation in terms of composition and molecular size being made. The molecular radius was derived and compared from different thermodynamic property and models. The Peng – Robinson and Soave – Redlich – Kwong equations of state were applied, in combination with different mixing rules for excess molar volume prediction. The accurate obtained results by means of cubic equations of state show the applicability of binary interaction parameters to estimate multicomponent excess molar volumes or any other properties by means of adequate thermodynamic derivations.