Here, [MB+]t is the concentration of MB molecules at time t, [MB+]o the initial MB+ concentration and k the first order rate constant. In order to perform electrolysis of MB+ solution, a two chamber reactor was used. Each of the chambers was equipped with 4 cm2 Pt electrode and the reference electrode was placed in the working electrode chamber. It was observed that insignificant bleaching occurred both in the working and in the counter electrode chambers in the potential range +0.1 V to +0.4 V irrespective of electrolyte used. The bleaching became significant at higher potentials (>+0.6 V) in the working electrode chamber in the presence of KCl. On the other hand, inconsequential decolorization was noticed in the presence of nitrate ions. In order to figure out the dependency of potential on bleaching of MB molecules in the presence of KCl, controlled potential electrolysis was carried out at the working electrode as shown in Fig. 4. It was noticed that rapid bleaching processes took place at the working electrode chamber in the presence of KCl when the potential was exceeded + 0.6 V, which reached in a maxima at +1.0 V (k: 78.2 × 10−3 min−1). At higher potentials than +1.0 V, the rate constant was found to decrease, which might be because water oxidation inhibited the hypochlorite formation. This effect was not observed when KNO3 was used as supporting electrolyte in place of KCl. In the presence of KNO3, decolorization rate was sufficiently low throughout the potential range. This observation indicates that at potentials higher than +0.6 V at the working electrode, hypoclorites were generated that caused chemical oxidation of MB molecules in the presence of KCl.