The topic of this paper is the air dehumidification process. At the first part of the paper, a description of the concept of humid air is given, as well as the basic physical parameters of humid air. Changes of the state of humid air in Mollier's hx diagram are also described and shown. Two calculations are carried out in the paper. One analysis shows what happens to the process when the temperature to which humid air is cooled is changing, while the initial temperature, relative humidity and amount of dry air are constant. While the second analysis shows what happens to the process when the initial relative humidity of the air changes, and the initial temperature, the temperature to which the humid air is cooled, and the amount of dry air are constant. At the end, it is shown how the changes in the parameters affected the dehumidification process, and the conclusion is given as to what should be aimed for in order to make the process as efficient as possible, which ultimately results in lower energy costs.