Electrolyte is one of important factors in the electrolysis for decolorization. NaCl was more effective than NaHCO₃ or Na₂SO₄. The decolorization characteristics of melanoidine, caramel and polyphenolic compounds were studied. The decolorization efficiency (DE) of a caramel solution with NaCl was 1,000 to 2,000U · l · kC^-1 although that of a caramel solution decolorized with NaHCO₃ was 30. DE of molasses wastewater from alcohol distillery was the same order as caramel and was different from DE of melanoidine or polyphenolic compounds. The decolorization reaction was mainly occurred on the anode in the experiment separated using a salt bridge. And the effectiveness of NaCl addition was caused by a preferential oxidation against colored compounds and a high efficiency on the oxidation of organic compounds.