Emission spectroscopy was employed to observe O2 plasma generated by anAC discharge at pressures from0.15 to 0.5 Torr. The emission bands and lines show linear dependence over the entire pressure range. Electron temperature measurements were performed using a double Langmuir probe. Measured electron temperature was found to be inversely proportional to pressure.Within the plasma conditions under consideration, O2, O2 +,O, and O+ play a dominant role in the pulsed plasma process within the spectral range of (200-800 nm), and the importance of these components vary little under the conditions of the plasma studied in this work. Identification of the vibrational levels of the ïuï B3 excited state indicates that predissociation through a repulsive states coupling with the ïuï B3 state may be respon - sible for the depletion of upper vibrational levels of this state.