Molecular interactions between some amino acids (glycine, L-alanine, L-valine and L-leucine) and a pharmaceutically active ionic liquid domiphen DL-mandelic acid ([DOM][MAN]) in aqueous solution at various temperatures have been studied by means of volumetric, conductivity and spectroscopy measurements. Density data were used to derive standard partial molar volume, V-2,phi(0) standard partial molar expansibility, E-phi(0), standard transfer volume, Delta V-t(0), isobaric thermal expansion coefficient, alpha(0) and hydration number, n(H) of amino acids. On the basis of the experimental conductivity and fluorescence spectroscopy data, the aggregation behaviour of [DOM][MAN] in aqueous amino acid solutions was investigated. Critical micelle concentration, cmc, aggregation number, N-agg, some thermodynamic functions, Delta G(m)(0), Delta H-m(0), Delta S-m(0) and Delta C-p(0) of micellization for [DOM][MAN] have been obtained. Effect of concentration and temperature on the obtained parameters has been discussed. Binding constant K-b for amino acid-[DOM][MAN] complex estimated using the UV-vis spectroscopic data approved that the solute-solvent interactions were strengthened by elevating the size of alkyl part of amino acids. (C) 2019 Elsevier Ltd.