The enthalpies of mixing of six kinds of aqueous ami no acid solutions (Glycine, L-alanine, L-Valine, L-serine, L-threonine and L-proline) and aqueous glycol solution and their respective enthalpies of dilution have been determined at 298.15 K using flow microcalorimetry. The experimental data have been analyzed according to the McMillan-Mayer formalism to obtain the heterotactic enthalpic interaction coefficients (h(xy)). h(xy) coefficients have been discussed from the points of view of solute-solute interactions. (C) 2009 Elsevier B.V. All rights reserved.