By using sorption data for com in the range of 4.4-60°C, the temperature (T) variations of the GAB. model parameters (Mm, CBand k) were studied. As only the monolayer moisture (Mm) varied (decreased) with temperature, a generalized GAB equation of four total parameters was obtained. This, together with the Clapeyron equation allowed a method to calculate the heat of sorption (Lb) as a function of T and moisture content (M). For each temperature, Lb presented a maxinuin some 30% above the heat of vaporization of water (Lf), which occurred around the Mm, in congruence with the sorption theory. A similar behavior of Lbwas found using the Othmer method. In contrast, the Gallaher equation predicted an ever increasing Lbup to 3 Lfat very low moistures. The GAB-Clapeyron method is then proposed to calculate Lbas a function of M and T.