The Amplite. Fluorimetric Catalase Assay Kit provides a quick and sensitive method for the measurement of catalase activity. It can be performed in a convenient 96-well or 384-well microtiter-plate format and easily adapted to automation without a separation step. Catalase reacts with H2O2 to produce water and oxygen (O2). Amplite. Red also reacts with H2O2 to generate a red fluorescent product. Therefore the reduction in fluorescence intensity is proportional to catalase activity. The Amplite. Red substrate used in the assay enables a dual recordable mode. The fluorescent signal can be easily read by either a fluorescence microplate reader at Ex/Em = 540/590 nm or an absorbance microplate reader at ~576 nm. With the Amplite. Fluorimetric Catalase Assay Kit, we have detected as little as 30 mU/mL catalase in a 100 μL reaction volume.