In this paper, a new interpretative model for evaluating the interaction energy in Lewis acid-base systems is proposed. The interaction energy in such a model has only four molecular interaction capacity parameters as variables, i.e. two Hansen partial cohesion parameters (MPa(1/2)), delta(d) (dispersive) and delta(p) (polar), and two Drago parameters (kJ(1/2) mol(-1/2)), E (electrostatic) and C (covalent). The developed model includes a cavity energy term which is mainly dispersive. Experimental calorimetric data taking tert-butyl alcohol as a Lewis acid mixed in nine Lewis bases were used to verify the interaction energy balance sheet and the predicting quality of the proposed model.