Sorption isotherms of lupine at 25, 35, 45 degreesC were determined. Adsorption and desorption data were obtained at each temperature and no hysteresis was observed. The experimental method was a gravimetric static method. The results were fitted by the Guggenheim-Anderson-deBoer model. The monolayer moisture content (parameter of the model) was constant in the range of temperatures employed with a value of 0.0497 dry basis (d.b.). The isosteric heat of lupine was evaluated at several moisture content using the Clausius-Clapeyron equation and below a moisture content of 0.15 (d.b.) increases appreciably up to around 20 kJ/mol at very low moisture content. (C) 2003 Elsevier Ltd. All rights reserved.