This paper reports a new approach to the equilibrium isotherms for water sorption in food materials. Isotherms of 19 different materials taken from the existing literature have been examined. This approach is a chemical reaction engineering approach which allows a temperature dependence function for the water sorption isotherms of each material to be deduced, i.e. Equilibrium relative humidity (%) = 100.exp (- f(X,T)/RT), which has the familiar Arrhenius form. In the above equation, X is the water content on wet basis (%), T is the absolute temperature (K). The approach unifies rite dynamic process of drying and the terminal state of drying (i.e. the equilibrium state) in that the format of the rate equation for drying/wetting can be reduced to the equilibrium relationship.