The ribose, one of the most important reducing sugars and a constituent of the DNA, was used in the reduction of thionine in alkaline aqueous medium.The reaction was carried out spectrophotometrically,and the change in the optical density of thionine was recorded at variable conditions of dye concentration,reductant, and pH.A pseudo first-order rate reaction was observed to establish the reduction kinetics of the dye, studied at a pH range of 0.34-12.8 using HCl as the acid and NaOH as the alkali.It was observed that the maximum reduction of the dye occurs at the optimum pH of 12.8.