Electrochemical decolorization of Methylene blue (MB) molecules was studied at Pt electrode in presence of KNO3 and KCl as the supporting electrolytes under acidic condition. The KNO3 electrolyte displayed MB decolorization effect, where MB molecules exhibited two redox peaks at 0.48 V and 0.34 V, respectively, in cyclic voltammogram (CV). The features of redox couples indicated the dimerizationofMBmolecules.Inthissimplepreparationtechnique,alessamountofsampleloadingwas required, and the method displayed high efficiency toward decolorization of MB dye. This report indicates the possibility for improving the quality of wastewater discharged from textile and other industries.