Cayman's SOD Assay is a fast and reliable assay for the measurement of SOD activity from plasma, serum, tissue homogenates, and cell lysates. SOD activity is assessed by measuring the dismutation of superoxide radicals generated by xanthine oxidase and hypoxanthine in a convenient 96-well format. A key feature of the kit is the inclusion of a quality-controlled SOD standard. The standard curve generated using this enzyme provides a means to accurately quantify the activity of all three types of SOD (Cu/Zn, Mn, and FeSOD).