Oxalate Oxidase (OxOx EC 1.2.3.4) belongs to the cupin protein superfamily and catalyzes the conversion of Oxalate into H2O2 and CO2. It plays an important role for stress response in plants. For example, wood rotting fungi generates high levels of oxalate, causing plant rot in many crops including lettuce, soybean, dry bean, tomato, etc. Overexpression of OxOx in plants (e.g. tomato, soybean, lettuce and tobacco) is able to generate transgenic plants showing resistance to fungal pathogenesis. Accurate measurement of Oxalate Oxidase activity is valuable for mechanistic studies in plants and development of transgenic plants. Oxalate Oxidase Activity Assay kit provides a quick and easy method for the measurement of Oxalate Oxidase activity in various samples. In this assay, Oxalate Oxidase converts oxalate into hydrogen peroxide, which in turn, reacts with a probe and converter generating a fluorometric signal (535/587 nm). The generated fluorescence is directly proportional to the amount of active Oxalate Oxidase present in samples. The assay is simple, sensitive, high ?throughput adaptable and can detect less than 4 μU of oxalate Oxidase activity per sample.