Display omitted •Solubilities of Glycine, dl-alanine and l-threonine in aqueous (NH4)2SO4 were determined.•Relative solubility and salting-in/out constant were measured.•The standard transfer Gibbs energies, enthalpy, entropy were calculated.•The chemical contributions of free energies and entropies of the amino acids were computed and explained. In this article the equilibrium saturated solubility of glycine, dl-alanine and l-threonine in aqueous ammonium sulphate media at various temperatures were estimated. The standard transfer Gibbs free energies and different thermodynamic parameters were also estimated. Different interactions were analysed for the solvation of the amino acids in the experimental media to explain the mechanism of solvation. For dl-alanine and l-threonine, salting-in effect is observed at lower electrolyte concentration while at higher electrolyte concentration salting-out effect is observed at a particular temperature. The chemical stability of the amino acids in aqueous electrolyte mixture was explained to justify the experimental results.