Book excerpt: In the adsorption phenomenon the substances from the external environment the gas or liquid are absorbed by a solid surface (adsorbent). Adsorption is used to separate gaseous and liquid mixtures, for drying and purification of gases and liquids. This reference broadly explores the calculation of the equilibrium and dynamic characteristics of adsorption in porous bodies at the molecular level. Two new theories of statistical physics are presented, both developed by the author for the consistent description of the equilibrium distribution of molecules and dynamics of flows in complex porous materials to be able to solve a wide range of practical tasks in the development of new technologies.