Department of Chemistry, Agra College, Agra-282 002, India Manuscript received 16 June 2003, revised 11 October 2004, accepted 9 December 2004 Density and Viscosity of the binary liquid mixtures of n-propylamine with polar and non-polar solvents viz. acetone, ethyl alcohol, 1,4-dioxane, carbon tetrachloride, benzene and toluene have been measured at 303.15 K. From density and viscosity data the values of excess molar volume (VE), the excess viscosity (ŋE) and the excess Gibbs free energy of activation of now (ΔG#E) have been determined. The computed results have been fitted to Redlich-Kister polynomial equation. Further, the density and viscosity data have been theoretically analysed for the validity of several viscosity models. The main thrust of the study is to correlate the excess properties and the relevant interaction parameters with the nature of molecular interactions between the mixing components.