We report measurements of the absolute differential cross sections for charge-transfer scattering of 0.5-, 0.85-, 1.5-, 2.8-, and 5-keV O+ ions by O2 at scattering angles between 0.04¿ and 5.4¿ in the laboratory frame. Cross sections for both O+(4S) ground-state and O+(2D,2P) metastable ions are presented. The metastable differential cross section is somewhat more forward peaked than that for the ground state. Integral and total cross sections are also reported. The present O+(4S) cross section is consistent with previous measurements, but the present metastable-state cross section is found to be substantially lower than previously reported in this energy range. These measurements provide information relevant to model calculations of O+ precipitation into the upper atmosphere during geomagnetic storms. ¿ 2000 American Geophysical Union