Summary:\nHydrogen peroxide (H2O2) is a ubiquitous, toxic, metabolic by-product of aerobic respiration, oxidative stress, and oxidative injury. Cayman's Hydrogen Peroxide Assay Kit utilizes the well established xylenol orange detection method of quantifying the oxidation of ferrous ions (Fe2+) to ferric ions (Fe3+) by hydrogen peroxide. A unique feature of Cayman's assay is the inclusion of catalase as an H2O2 scavenger for the purpose of confirming the specificity of the reaction for H2O2. The sensitivity and the specificity of the assay make it well suited to accurately measure urinary levels H2O2 in a 96 well plate format. Each kit contains hydrogen peroxide, reagent 1, reagent 2, catalase, a 96 well plate, plate cover, and complete instructions.