Abstract Methyl clupanodonate has been oxidised with potassium permanganate in acetone solution. Among the oxidation products propionic acid, acetic acid, succinic acid and methyl hydrogen succinate have been identified. Of these compounds acetic acid is believed to be formed by the secondary decomposition of malonic acid. Accordingly the presence of above-mentioned oxidation products gives an indication of the presence of the following groups in clupa-nodonic acid jointed by ethylenic linkings thus: CH3·CH2·CH=, =CH·CH2CH=, three of =CH·(CH2)2·CH=, and =CH·(CH2)2·COOH. These results agree fully with those obtained in a previous experiment of the ozonolysis of amyl clupanodonate.