The kit is designed to measure catalase activity in biological samples. Background: Catalase is an enzyme present in blood and other tissues with antioxidant activity. This enzyme can catalyze the reaction that consumes hydrogen peroxide, transforming it into water and oxygen. Since hydrogen peroxide is difficult to be measured directly in biological samples, the determination of these detoxifying enzymes has been widely used in substitution. Catalase activity levels are also related to antioxidant capacity. Catalase enzyme performs a reaction giving rise to a compound that forms a complex with the chromogen. This reaction produces a purple color directly proportional to catalase activity that can be determined by means of a simple and fast spectrophotometrical measure.