For dehumidification process, sorption process is commonly applied. Mathematical modeling can be implemented in order to assist in minimization of energy consumption and better process design. In this study, the reaction engineering approach (REA), which has been proven to model various challenging drying process successfully, is developed and implemented for the first time to model completely reverse process of drying. The equilibrium activation energy (ΔEv,b) is evaluated according to the environmental temperature and humidity and combined with the relative activation energy to describe the wetting process. Interestingly, the relative activation energy generated from one accurate drying/desorption run can be used to describe accurately the water vapor sorption/wetting process. The REA implemented as the mass balance is combined with the heat balance incorporating the heat of sorption. A good agreement between the predicted and experimental data is shown. The REA is able to model accurately the wetting process. The applicability of the REA could be because of the flexibility of the relative activation energy to capture the environmental conditions and reflect this in the change of internal behavior, similar to the relative activation energy used for intermittent drying process. This indicates that the relative activation energy can be used as fingerprint of both drying and water vapor sorption process.