The main goals of studying the kinetics of enzymatic processes are to establish their elementary mechanisms, namely, the succession and rate of intermediate of elementary stages as well as their chemical nature. To determine the parameters of the Michaelis–Menton equation, a whole arsenal of classical and modern physical methods described in Chap. 2 is used. In parallel, the following groups of methods are also successfully applied: (1) Continuous flow, temperature, pH and pressure jumps, kinetic isotope effect (KIE), artificial intermediates, and transition state analogs methods. Of particular importance are theoretical computation approaches. Foundation of these approaches, combined quantum mechanics/molecular mechanics (QM/MM) methods in computational enzymology, in particular, and examples illustrated theoretical approaches are subject of consideration in separate sections.