Measurements of single electron capture cross sections by Ar2+ ions in thin targets of neon, argon, and krypton have been made with an absolute accuracy of about 5%. The detection system was constructed so as to have a uniform efficiency over the range of angles and energies at which the singly charged Ar+ ions were produced in the charge exchange. Discrepancies with the extrapolated absolute values of previous measurements were found, but the energy variations of the cross section are in much better agreement. It seems possible to account for the energy variation of the cross sections with the two state theory when it is assumed that the ions of both the initial and the final states are all in their ground states.