The different factors that produce evaporation of moisture from a capillary porous medium are being investigated. Thermodynamic measurements of the porous medium-air-water system and a mathematical model have permitted the establishment of some correlations between the principal non-dimensional numbers associated with heat and mass transfer between the evaporating water in the porous medium and the external gas stream. These correlations lead to the prediction of some important parameters such as the depth of the surface of vaporization and the exchange coefficients of the heat and mass transfer during the evaporation from a capillary porous medium.