A numeric kinetic model of the horseradish peroxidase catalyzed hydroxylation of phenol is proposed to complete the previous thermodynamic analysis. As previously stated, the basic role of HRP is to catalyze the production of DHF. radicals. These further form hydroxyl radicals that hydroxylate phenol via noncatalyzed reactions. The transient differential equations of the model are solved numerically. Several kinetic constants are adjusted to fit basic experimental data. This set of values is then kept constant to simulate additive experiments carried out under different conditions. Predictions of the model concerning the effects of HRP concentration, temperature variation, and presence of catalase and superoxide dismutase are consistent with the experimental results. The quantitative kinetic approach consequently fully confirmed the previous thermodynamic conclusions.