The fundamental approach to the description of the kinetics of chemica
l reactions has been considered, and principle of chemical reaction in
dependence and active mass law have been taken into account. Models fo
r rate constants of elementary reaction have been discussed on the bas
is of the collision theory, the theory of activated complex, and the t
heory which takes into account the movement of intermediate particles
to the reaction barrier, The collision theory is suggested for use at
high temperatures, the theory of activated complex is recommended for
application at moderate temperatures, and the theory which takes into
account the movement of intermediate particle to the reaction barrier
is relevant to low temperatures. It is emphasized that the principle o
f maximal change of free energy, which was suggested earlier, may be a
pplied for analysis of the mechanism of chemical processes.