Densities and viscosities of binary mixtures of propanoic acid with N,N-dimethylaniline and N,N-diethylaniline including those of pure liquids have been measured at (303.15, 313.15, and 323.15) K over the entire composition range. From these experimental values, deviations in viscosity and excess molar volumes have been computed and fitted to Redlich-Kister type polynomial. The corresponding standard deviations have been calculated. The experimental data of viscosity have been used to test the applicability of the empirical relation of Grunberg-Nissan for all of the systems studied. Molecular interactions in the liquid mixtures have been investigated in light of the variation of deviation and excess values in the evaluated properties.