In photochemical oxygenation of cyclohexane by KVO3−CF3COOH or K2Cr2O7−Bu4NBr−H2O−CH2Cl2 in air the source of oxygen atoms in the product cyclohexanol and cyclohexanone is air dioxygen rather than a metal oxo-complex. In the absence of dioxygen the products of alkane oxygenation are not formed in either of the above systems. At pH=3, Cr(VI) does oxidize cyclohexane to cyclohexanol even in argon atmosphere.