Moisture adsorption-desorption isotherms (EMC/e.r.h.) of Citrus aurantium leaves were determined at 30, 40, and 50degreesC using the standard gravimetric static method over a range of relative humidity from 0.05 to 0.9. The experimental sorption curved., were fitted by six equations: modified Chung-Pfost, modified Halsey, modified Oswin, modified Henderson, modified BET, and GAB. The modified Halsey and the modified BET models were found to satisfactorily describe the desorption isotherms of Citrus aurantium leaves. For adsorption, GAB and modified BET models were the best fit. The net isosteric heats of sorption of water were determined from the equilibrium data at different temperatures. (C) 2004 Elsevier Ltd. All rights reserved.