The photolysis of benzene/ozone mixtures in an argon matrix at 12 K with UV light of lambda greater than or equal to 280 nm leads to the following products: phenol, 2,4-cyclohexadienone, benzene oxide, and butadienylketene (hexa-1,3,5-trien-1-one). The identification of butadienylketene as a product is based on deuterium isotopic shifts and agreement with density functional vibrational frequency calculations. We find an average phenol/butadienylketene branching ratio of 4.3 during the course of photolysis. This is the first report in the literature of the observation of a ketene product from the reaction of oxygen atoms with benzene.