In the reaction mixtures of the oxidation of hept-3-yne with molecular oxygen as products of the attack on the C-C triple bond heptane-3,4-dione, propionic and butyric acids and a very small amount of 2-ethylvaleric acid were found.Hept-2-en-4-one and hept-3-en-5-one were probably present, but could not be identified unambiguously.As in the case of the isomeric octynes the main primary reaction products were the hydroperoxides formed by attack on the C-H bonds in α-position to the CC triple bond.