Usage of TOOS: water-soluble reagents for enzymatic spectrophotometric determination of hydrogen peroxide. New type of Trinders reagent is a high-water-soluble aniline derivatives, is widely used in diagnostic tests and biochemical tests. It has several advantages compared with conventional chromogenic reagents in the colorimetric determination of hydrogen peroxide. New type of Trinder’s reagent is very stable and could both be used for solutions and testing pipeline inspection system. In the existence of hydrogen peroxide and peroxidase, the new Trinder’s reagent and 4-amino-antipyrine (4-AA) or 3-methyl-benzothiazole sulfone hydrazone (MBTH) will produce very stable purple or blue dye by oxidative coupling. Its molar absorbance ratio with MBTH dye-coupling is 1.5-2 times higher than with 4-AA dye coupling, but 4-AA solution is more stable than MBTH solution. Substrate produces hydrogen peroxide by its oxidase through enzyme-induced oxidation. The concentration of hydrogen peroxide corresponds to the concentration of substrate. Thus, the amount of substrate could be determined by the coloration of oxidative coupling reaction. Glucose, alcohol, acyl-coenzyme A and cholesterol can be used to detect substrate which coupled with the new Trinder’s and 4-AA. TOOS is the most commonly used in the 10 new Trinder’s reagents. To a particular substrate, it is essential to test different types of new Trinder’s reagent for the development of best testing system.