Contact transfer charge (CCT) absorption spectra ofN,N-dimethylformamide (DMF) andN,N-dimethylacetamide (DMA) with molecular oxygen (O2) have been investigated. These solvents form contact complexes with O2and have strong ultraviolet CCT absorption bands with intensities that are related to the partial pressure of the applied O2and the mole percentages of DMF and DMA in DMF/acetonitrile (MeCN) and DMA/MeCN mixtures, respectively. Electron spin resonance spectra and luminol chemiluminescence tests confirm the absence of the formation of superoxide ions from oxygenated DMF and DMA solutions.