The densities, rho and speeds of sound, u of the binary mixtures of 2-pyrrolidone with 1,2-propanediol and 1,3-propanediol, including those of pure liquids, have been measured over the entire range of composition at temperatures, (303.15-323.15) K and atmospheric pressure. Using the experimental data, excess molar volumes, V-m(E), excess isentropic compressibility, kappa(E)(s), excess speeds of sound, u(E) and excess molar isentropic compressibility, K-s,m(E) were calculated. The partial molar volumes, (V) over bar (m,1) and (V) over bar (m,2), partial molar isentropic compressibilities, (K) over bar (s,m,1) and (K) over bar (s,m,2), excess partial molar volumes, (V) over bar (E)(m,1) and (V) over bar (E)(m,2) and excess partial molar isentropic compressibilities, (K) over bar (s,m,1) and (K) over bar (s,m,2) over whole composition range; partial molar volumes, (V) over bar degrees(m,1) and (V) over bar degrees(m,2), partial molar isentropic compressibilities, (K) over bar degrees(s,m,1) and (K) over bar degrees(s,m,2), excess partial molar volumes, (V) over bar degrees(E)(m,1) and (V) over bar degrees(E)(m,2) and excess partial molar isentropic compressibilities, (K) over bar degrees(E)(s,m,1) and (K) over bar degrees(s,m,2) of the components at infinite dilution have also been calculated. The results have been discussed in terms of intermolecular interactions prevailing in these mixtures. The results indicated that the interactions in these systems follow the order: 1,2-propanediol > 1,3-propanediol. The speeds of sound of these mixtures have been analysed by using scaled particle theory and the results are compared with experimental findings. (C) 2017 Elsevier Ltd.