Measurements of density (ρ), viscosity (η), and ultrasonic velocity (u) were carried out on a-amino acids, L-lysine, L-glutamine, L-arginine (0.1– 0.5 mol kg -1), in 0.2 mol kg-1 aqueous magnesium nitrate at 298.15, 303.15, 308.15,and 313.15 K. These measurements were carried out to evaluate some important parameters, viz., adiabatic compressibility (β), apparent molar compressibility (φK), apparent molar volume (φV), limiting apparent molar compressibility (φK0), limiting apparent molar volume (φV0), and their constants (SK, SV) viscosity A and B coefficients of Jones-Dole equation. These parameters were interpreted in terms of solute-solute and solute-solvent interactions and structure-making/breaking ability of solutes in the given solution.