The density (rho), speed of sound (u), and refractive indices (n(D)) data at atmospheric pressure for benzene + n-heptane + n-octane mixtures from 298.15 to 318.15 K have been measured. The data were further used to derive excess molar volume (V-m(E)) and deviation in u (Delta u) and n(D) (Delta n). The V-m(E) values for the ternary mixtures were positive and predicted from the constituent binary data using various fitting equations, geometrical solution models, and the Prigogine-Flory-Patterson theory. The u data at 298.15 K were analyzed by Schaaff's collision factor theory and Nomoto correlations. Using the Jacobson free length theory, L-f(E) and V-a(E) were also calculated. The n(D) data for these mixtures were also predicted from the pure component data.