Density, sound velocity and electrical conductivity of solutions of tri-sodium phosphate (Na 3 PO 4 ) in 1-propanol+water mixed-solvent media with alcohol mass fractions of 0.00, 0.05, 0.10, and 0.15 are reported in the 283.15–303.15K temperature range at 5K intervals. From the experimental density and sound velocity data, the apparent molar volume and isentropic compressibility values of tri-sodium phosphate are evaluated and fitted to a Redlich+Meyer type equation from which the apparent molar volume and apparent molar isentropic compressibility of the solutions at the infinite dilution are calculated at working temperature. The results show a positive transfer volume of Na 3 PO 4 from an aqueous solution to an aqueous 1-propanol solution. The apparent molar isentropic compressibility of Na 3 PO 4 in aqueous 1-propanol solutions is negative and it increases with increasing concentration of Na 3 PO 4 , 1-propanol and temperature. The effects of the electrolyte concentration, temperature and relative permittivity of the medium on the molar conductivity are also investigated. Comparisons between the results obtained in this work are made with those for Na 2 HPO 4 and NaH 2 PO 4 obtained in our previous works.