OxiRed, which has been marketed under the name Amplex Red™ reagent, is a highly sensitive and stable probe for H₂O₂, is a fluorogenic (EX/EM = 535/587 nm) and Colorometric (l = 570 nm) substrate for peroxidase. In the presence of horseradish peroxidase (HRP), the OxiRed probe reacts in a 1:1 stoichiometry with H₂O2 to produce highly fluorescent resorufin. Because H₂O₂ is produced in many different enzymatic reactions, the OxiRed probe allows researchers to detect the activity of many different enzymes either colorimetrically or fluorometrically.