Organic matters in waste liquor are oxidatively decomposed by microorganisms and non-biological chemical reactions. It is necessary to determine the oxygen demanded for the oxidative decomposition. As one method for measuring chemical oxygen demand (COD), permanganate oxidation is mainly used in Japan, and the procedure is authorized as Japan Industrial Standard (JIS). We tested utilities of the method using soluble starch, egg white albumin, lignosulfonate solution and their mixtures with metal sulfate as model of waste liquor. COD of these macromolecules were variously changed by the addition of metal ions. Above all, COD of soluble starch solution was remarkably diminished by divalent ions, such as Cu^2+ and Mg^2+, trivalent ion Fe^3+ and monovalent K^+. The extent diminished was about 40% in each mixture. Such conspicuous diminution of COD was not found in albumin-or LSA-metal ion mixture. COD of LSA-Cu^2+ mixture augmented more than that of LSA solution by a factor of 1.1. In the mixture containing two sorts of macromolecules, COD also diminished by the addition of metal ions. These experimental results show that COD of the macromolecule solution measured can resist against permanganate oxidation. As this poorly-oxidizable complex was not conformed irreversibly, COD of the starch-metal mixture, above all, gradually increased as time passed. These experimental results show that COD of the macromelecule solution measured by permanganate consumption (JIS method) changes and always diminishes remarkably by the co-existence with other macromolecule and metal ion. Then, it may be concluded that JIS method can not be successfully adopted as a general one to analyze many kinds of waste liquor which varies the sorts and the content of organic and inorganic matter. The incompleteness of the method is due to the weak oxidative potentiality of permanganate reagent. Development of rapid COD analytical methods using more stronger oxidizing agent such as dichromate are claimed. Measurement of TOC (total organic carbon) is more favorable as the more strict indicator of water-pollution control, though the analytical procedure is yet unsettled.