One of the main characteristics of the chemical reaction is the rate of reaction. In order for chemical reaction to start, first molecules must get in touch with one another, and must come to a successful collision of reactants. The number of these successful collisions in time determine the rate of a chemical reaction. In this thesis, the main concepts related to the speed of chemical reactions are described together with reaction rate theories. Each reaction followskinetics of particular order, so we can classify reactions as the zeroth-order, first-order, second-order and the third-order reactions. This thesis also elaborates factors that influence rate of chemical reactions as well the importance of the reaction rate in everyday life.