The UV absorption spectra of the mixtures of aromatic compounds-benzene, toluene, isobutylbenzene, p-xylene, xylene (mixture), mesitylene, aniline, benzaldehyde, and anthracene with molecular oxygen have been investigated.It was found that in agreement with the observation of Evans, charge-transfer spectra were observed for all of the mixtures, with the exception of those of anthracene and of benzaldehyde.The frequenties of these charge-transfer spectra vary linearly with the ionization potentials of the organic compounds.