Two autodetaching states of O- have been found by observing the electron energy spectrum of O- ions excited in collisions with a He target at keV beam energies. The energies of the states have been measured as 10. 112 and 12. 115 +/- 0. 010 eV. The H- 1S, 3P, and 1D autodetaching states below the n=2 hydrogen level are excited in O- on H2 collisions, and the Ar- autodetaching states below the first excited argon level are formed in O- on Ar collisions. No structure in the electron energy spectrum was seen for collisions of O- on O2 or Ne.