Till date most acceptable method of estimation of dissolved oxygen in water sample is Winklar’s method (APHA-2005). The method of calculation of data is followed by the formula V1x N x E x 1000/ V4 (V2- V3/V2). Where, V1= Quantity of the sample water. V1 = Quantity of sodium thiosulphate used in titration. N = Normality of sodium thiosulphate (N/80). V4 = Quantity of sample taken for titration. V3 = Quantity of alkaline iodite and manganese sulphate. E = Equivalent weight of O2. This formula can not explain a clear picture related to the chemical reaction takes place within the reagents used in this methodology. Therefore, an attempt has been made towards chemical deduction of data, available during estimation.