The effect of the chemical composition of short residues, a feedstock for the manufacturing of airblown asphalt on the yield of the byproduct black furnace oil was studied. It was shown that paraffin-naphthene hydrocarbons present in short residues are the major source of the formation of black furnace oil. It was found that the paraffin-naphthene hydrocarbons remaining unreacted during the oxidation of asphalts make up a considerable portion of the black oil produced upon asphalt manufacturing.