Catalase is an ubiquitous antioxidant enzyme that is present in most aerobic cells. It is involved in the detoxification of H2O2, a ROS that is a toxic product of both normal aerobic metabolism and pathogenic ROS production. Cayman’s Catalase Assay utilizes the peroxidatic function of catalase for determination of enzyme activity. The assay can be used to measure catalase activity in plasma, serum, erythrocyte lysates, tissue homogenates, and cell lysates.