AbstractN‐Hexane and 2,3‐dimethylbutane were oxidised separately and as a mixture, in the liquid phase by oxygen at 160°, under 25 atm. pressure and in the presence of 0·30 wt.‐% of manganese as the naphthenate. The variables of the reaction which influence the yield of acetic acid and acetone were studied. It has been shown that the co‐oxidation of a mixture of linear and branched hydrocarbons increases the yield of useful products, and the rate of oxidation. The effect of the molecular structure of the hydrocarbons in the co‐oxidation systems is briefly discussed in relation to the theory of the degenerately branched chain reactions.