The aim of this paper is to present the equations of drying theory for saturated capillary-porous materials, in which the potentials of liquid and gas phase responsible for the mass transfer and phase transitions appear in a natural way. The main part of the paper is devoted to construction of the rate equations for heat and mass transfer on the basis of mechanics of continua and the thermodynamics of irreversible processes. The final system of equations is given and the boundary conditions for heat and mass transfer are discussed.