Doubly charged ions were observed during the decay period of plasmas produced in neon as well as in argon at reduced gas pressures ranging from 0.14 to 1 Torr. The measured time dependence of both the Ne2+ion density and the Ar2+ion density were corrected for the effect of diffusion cooling of the electrons. The reaction rate constant for the partial charge exchange reaction Ne2++Ne→Ne++Ne+was found to bek=(9 ± 2) × 10−14cm3sec−1. For the reaction rate of the similar reaction in argon, only an upper limit could be obtained. The value of the mobility of Ne2+in neon was found to be &mgr;(Ne2+)=6 ± 1 cm2/V sec. The value of the mobility of Ar2+in argon was consistent with previously published data.