In this works, we are interested in the modeling of sorption (adsorption and desorption) isotherms in the gas phase using the model based on the statistical physics formalism and some working hypotheses. The modeling is first of all to establish analytical expressions simple ones describing the experimental isotherms of the products selected agricultural products, to adjust them and finally to look for the statistical model. The different calculated parameters through an adjustment procedure allow us to determine; the number of molecules per site, the density of receptor sites, the three energetic parameters and the number of layers, and the model applied to calculate the specific area as well as. Based on the statistical model, we describe the adsorption process at the microscopic level, from the point of view stereographic and energetic, with the values of the parameters adjusted as well as the thermodynamic functions involved in the adsorption and desorption process. Based on the model of desorption we determined the PSD and the AED.