Moisture sorption isotherms of green and red peppers were determined at three different temperatures (30 degreesC, 45 degreesC and 60 degreesC) and relative humidities (10-90%), using the standard static, gravimetric method. The GAB, Halsey, Oswin and BET sorption models were tested to fit the experimental data. A nonlinear regression analysis method was used to evaluate the constants of four sorption equations. The Halsey equation gave the best fit to the experimental sorption data for a wide range of water activity while BET gave the best fit for a water activity range of 0.1-0.5. The agreement between experimental and calculated values was found to be satisfactory. The isosteric heats of desorption and adsorption of water were determined from the equilibrium data at different temperatures using the Clasius-Clapeyron equation. (C) 2000 Elsevier Science Ltd. All rights reserved.