Abstract <p>The Fenton reaction is of considerable interest because it can be used in chemical, biochemical, and biomedical research. The Fenton reaction allows us to estimate the content of hydroperoxides&#xa0;in a sample. Such studies require knowledge of the characteristics of the reaction at different ratios between concentrations of hydroperoxides and divalent iron. The yield of the reaction is determined from its сhemiluminescence. The number of oxidation acts of N(Fe²⁺ → Fe³⁺) in the Fenton reaction is calculated for cases of [Fe²⁺] &gt; [H₂O₂] and [Fe²⁺] &lt; [H₂O₂] at concentrations of Fe²⁺ and H₂O₂ ranging from 10⁻³ to 10⁻⁷ mol/L. It is shown that the concentration of peroxide can be determined unambiguously only when [Fe²⁺] &gt; [H₂O₂]. With [Fe²⁺] &lt; [H₂O₂], it is not always possible to determine the complete yield of сhemiluminescence due to a strong drop in the rate of the reaction. The kinetics behind the formation of the luminous product in the Fenton reaction after introducing luminal to enhance the glow is calculated.</p>