The double photoionization spectrum of SO2 has been measured using the TOF-PEPECO technique and contains one resolved band. Detailed electronic structure calculations and experimental comparisons allow the resolved band to be identified as the A (1)A(2) state of the SO22+ dication, with its adiabatic ionization energy at 35.284+/-0.02 eV. According to the most accurate calculations, the ground state level of SO22+ must be located near 33.48 eV, well below the range accessed by vertical transitions from neutral SO2. Transient SO22+ molecules detected by mass spectrometry may be identified either as the sharp levels of the A (1)A(2) state or as ground state levels populated by nonvertical ionization pathways. (C) 2004 American Institute of Physics.