In other to solve the problem of fake drugs which is rampart in Nigeria, there is need for a method of drug analysis which is simple, fast and cost effective. Niacin drug is easily adulterated due to its nature and high demand. This requires that its degree of purity be certified before usage. In this book, researchers developed a simple spectrophotometric method and kinetic model for the assay of niacin. The book describes the assay of niacin which is based on charge transfer complexation (CT) reaction of niacin as n-electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) as -electron acceptor in methanol. The method was successfully applied for the quantitative determination of niacin in pure and commercial forms.