Densities and viscosities of the binary mixtures of the tributyl phosphate + hexane and tributyl phosphate + dodecane systems have been experimentally determined at different temperatures and atmospheric pressure, over the entire composition range. Other mixing properties such as the excess molar volumes and the viscosity deviations have been also obtained for each of the systems. The excess molar volumes (V (E)) and viscosity deviations (Delta eta) have been fitted to the Redlich-Kister equation, and the coefficients and estimate of the standard error values are presented. A discussion on these quantities in terms of molecular interactions is reported.