Pulsed laser excitation of contact charge transfer pairs of hexamethylbenzene (HMB) and oxygen in methanol-acetonitrile gave no evidence for intermediacy of reactive species such as HMB radicalcations and pentamethylbenzyl cations (ArCH2+), though stationary irradiation of the pair in hydroxylic solvents afforded distinct products arising from the cationic species. The mechanism of reactions was discussed