A study has been conducted to evaluate the effect of addition of interesterified fat, polydextrose, maltitol, and FOS-sucralose on adsorption isotherm and thermodynamic properties of multigrain high fiber reduced calorie biscuits (HFRCB). A static gravimetric method was used over a water activity range of 0.11-0.95 at three different temperatures (25°C, 35°C, and 45°C). The adsorption isotherm of HFRCB showed a slight shift from type II curve to type III. The BET and GAB models were found as the best fitted to the experimental data. The net isosteric heat of sorption of HFRCB varied from 5.07 to 25.45 kJ/mol. The net isosteric heat of sorption of first water molecule and characteristic moisture content of HFRCB was 27.43 kJ/mol and 0.11 kg/kg dry solids, respectively. The spreading pressure increased with increasing water activity and temperature. Entropy-Enthalpy compensation theory was evaluated for sorption isotherm of HFRCB at studied experimental conditions. How to cite this article: Padinjarakoot N, Sabikhi L, Panjagari NR, Kumar CTM. Adsorption isotherm and thermodynamic properties of high fiber reduced calorie multigrain biscuit. J