The behavior of CF2radicals in CF4/O2plasmas has been studied as a function of the oxygen partial pressure in an rf reactor with 13.56 MHz, 30 W, and 40 mTorr total pressure. The CF2ground and excited states were detected by the CF2(A‐X) band spectra applying laser‐induced fluorescence and optical emission spectroscopy, respectively. Adding oxygen to the CF4feed gas, the intensity of the CF2signals in both spectra showed similar decrease. No evidence is found for a simple correlation between the neutral CF2densities and the CF+2ions measured by quadrupole mass spectrometry. Electron densities and temperatures were evaluated to be slightly above 8×109cm−3and ∼5 eV, respectively. A simplified model, which takes into account different excitation paths, suggests that direct electron impact of the CF2ground state species was the dominant mechanism for the population of the electronically excited state. Absolute CF2and O concentrations depending on the oxygen feed could be estimated. We obtained CF2densities between 2×1013and 2×1012cm−3, when the oxygen concentration increases from 2% to 23%. The corresponding O densities varied from 1012to 6×1013cm−3.