Compounds between trifluoromethanesulphonates and HMPA were prepared by reaction of the salt and ligand dissolved in ethanol and acetone, respectively, on water bath. The compounds are characterized by CHN, IR and TG. From solution calorimetry and appropriate thermodynamic cycles, the standard molar enthalpies of acid-basic reaction adducts have been determined. Calorimetric measurements were performed using a Solution Calorimeter System, at 298.15 K, in ethanolic solution,