Alkali metals have been used to degrade SF 6 in liquid ammonia. The products include metal fluorides. In this study, we reacted K − and Ag − with SF 6 in a triple quadrupole mass spectrometer. The atomic metal anions were formed by in-source collision-induced dissociation (CID) of their respective oxalate salts as previously described by our group. The only two reaction products observed were SF 6 − and SF 5 −. At low collision energy, the latter was deduced to be formed via an abstraction by the metal of F from SF 6 − formed by electron transfer in the encounter complex between the metal anion and neutral SF 6. As the collision energy was increased, there was evidence of a CID contribution to SF 5 − directly from SF 6 −.