Advanced oxidation processes (AOPs) have gained popularity and are being extensively used for the degradation of micropollutants. The importance of 2nd order reaction rate constant of hydroxyl radicals with micropollutants (kOH) in AOPs is undisputable. The degradability of a micropollutant by an AOP can be predicted from its kOH along with other physicochemical properties, and hence are important for the design of water treatment chains. Furthermore, a micropollutant with known kOH value can be used as a probe compound to assess AOPs. In this work, the kOH of 212 micropollutants are reviewed. An overview is also provided on the generation of hydroxyl radicals, significance of kOH, and the typical methods used to determine kOH.