An efficiency study about the horseradish peroxidase (HRP) activity over Brilliant Blue-G (BB) decolorization with hydrogen peroxide was achieved through kinetic analysis. Differential and extended kinetic curves were used for assessing the inactivation paths and for optimizing the overall degradation process. The catalytic and the specificity constants estimated via Michaelis-Menten model demonstrated that HRP is highly efficient in dye decolorization, although operational inactivation due to formation of degradation products still occurred. It was noticed that the bicarbonate anions exerted protective effects on the enzyme inactivation caused by the oxidizing substrate but affected less the inactivation due to the degradation products of BB.