In this work an air dehumidification desiccant system is investigated. A two-dimensional unsteady state numerical model is developed for the simulation of the heat and mass transfer phenomena in a representative channel of a desiccant wheel. A set of operating cases with known experimental results are simulated with the numerical model. An acceptable agreement between the results experimentally and numerically predicted is found. Parametric studies are conducted regarding the influence of operating parameters on the performance of the desiccant wheel. The air dehumidification desiccant system is simulated in order to predict the electrical energy required for fan operation and to drive the wheel, as well as the thermal energy for the heating of the regeneration airflow. Several parametric studies are performed toward the characterization of optimum performance of the overall system considering two criteria as: (i) the minimization of the humidity ratio of the supply process air and (ii) minimization of the specific adsorption energy. The optimum point of case one is at the lowest wheel speed (4 Rph) and middle regeneration temperature (97 °C) whereas for case two, the optimum point happens at the highest regeneration temperature, regeneration flow rate desiccant wheel speed, and moderate process volume airflow (0.65 m/s).