Process of extraction, chemistry of extraction and a short way to its development, application spheres, extragents of various class and requirement to them were comparatively investigated and examined. It has been established that the directed development of investigations in chemistry of extraction is determined by requirement of experiments. It has been established that problems of theory of extraction coincide with the problems of theory of chemical reactions in solvents. That’s why the basic task is to establish reasons of the observed stoichiometry, find regularities of changes of reactivity in reactions with different compounds and description of molecular mechanisms of extraction reactions.