The volumetric, acoustic and viscometric methods are used for investigating the interactions of L-aspartic acid (Asp) in aqueous solution of 1,2-propanediol (PD) over a temperature of (298.15, 303.15 and 308.15) K at atmospheric pressure. Using the experimental results, the apparent molar volume, V φ , limiting apparent molar volume, V 0 φ , the slope, S v , and partial molar volume of transfer, V 0 φ,tr, have been calculated from density data. The apparent molar isentropic compressibility, K φ , s , limiting apparent molar isentropic compressibility, K 0 φ,s , its slope, S k , and partial molar compressibility of transfer, K 0 φ,s, tr , have been calculated from speed of sound data. These values are also used for calculating the number of water molecules hydrated, n H , to the Asp. The viscosity data has also been used to determine relative viscosity η r , viscosity B-coefficients, temperature derivative of B-coefficients, dB/dT and viscosity B-coefficients of transfer, B tr . The calculated parameters have been discussed in terms of various solute-solute and solute-solvent interactions prevailing in these solutions. Further, a detailed insight into the physicochemical interactions between Asp and aqueous PD, e.g., ion-hydrophilic and hydrophilic-hydrophilic interactions along with the structure-making tendency have been retrieved through the perusal of these calculated parameters.
