The ion-molecule equilibrium method has been applied to studies of the gas phase fluorine exchange reactions between fullerene anions and metal fluoride anions. This has yielded the first quantitative determination of the absolute values of Gibbs energies for addition of fluorine to the anions of higher fullerenes C-70+2n(-) (n = 0, 1, ..., 7) and sequential fluorine addition in the series C60Fn- (n = 0, 1, 2) Estimates for C-F bond dissociation energies of C60F2 and C70F2 and electron affinities of monofluorinated [60]- and [70]fullerenes in the gas phase are reported.