Viscosities and densities of four binary mixtures tri-n-butyl phosphate+benzene, +carbon tetrachloride, +isobutyl methyl ketone and +acetylacetone have been measured at 25, 30, 40 and 45-degrees-C at six mole fractions of each mixture. From the experimental data excess viscosities DELTAln eta, excess Gibbs energies of activation DELTAG*E of flow, excess entropies of activation DELTAS*E of flow, and excess molar volume V(E) have been calculated. The molecular interactions in these mixtures are explained considering relative magnitude of these parameters.