The enthalpies of mixing of glycine, L-alpha-alanine, L-gamma-aminobutyric acid, L-alpha-valine, L-alpha-serine and L-alpha-threonine with cyclohexanone in aqueous solutions and their respective enthalpies of dilution have been measured by calorimetry at 298.15 K. Experimental enthalpies of dilution and mixing have been correlated with the virial expansion equation that was obtained with the MeMillan-Mayer theory. The enthalpic interaction parameters h(xy),h(xxy) and h(xyy) of the amino acids studied with cyclohexanone in aqueous solutions have been evaluated, and the heterotactic enthalpic pair interaction coefficients (h(xy)) are discussed in terms of solute-solute interactions. (c) 2006 Elsevier B.V All rights reserved.