The densities, ρ, viscosities, η, and refractive indices, n, of binary mixtures of benzene with 1-butanol, 2-methyl-1-propanol, 2-butanol, and 2-methyl-2-propanol, including those of the pure liquids, were measured over the complete composition range at 30° C. The dependence of ρ, η, and n on composition was checked by using an empirical relation. The experimental data were used to calculate excess molar volumes, VE, deviations in viscosity, Δ η, excess free energies of activation of viscous flow, G* E, deviations in refractive index, Δ n, apparent molar volumes, V ϕ, 1 and V ϕ, 2, and partial molar volumes,, of benzene in alcohols and alcohols in benzene, respectively, at infinite dilution. The variations of these parameters with composition and the effect of branching in alcohols were discussed from the point of view of intermolecular interactions in these mixtures.