In order to study the reactivity of particular excited states of O2+, we have studied the resonance enhanced multiphoton ionization of O2 via the 1,3Πg states with a frequency-doubled pulsed dye laser in the range 296.5–303.5 nm. We managed to produce a large ensemble of O2+ ions in selected v+,N+ states, with v+ = 0 or 1, and N+ up to 25. Such an ion source, with tunability and selectivity of the output rovibrational state, can be coupled to a storage device in order to study the collisional and radiative properties of infrared inactive species.