Cross sections for charge-exchange reactions of potential importance in the Io torus and the interaction of torus plasma with Io's atmosphere and estimated with an accuracy of about a factor of 2. The size of the cross sections for a given collision velocity are shown to depend entirely on the spacing of the energy levels between the initial and final states of the reactions. Reaction rates for charge-exchange cross sections, calculated at the corotation velocity in Io's reference frame, are compared to reaction rates for electron impact ionization and recombination at a number of radii from 5.1 RJ to 7.1 RJ for a model torus. Inside Io's orbit, charge-exchange processes are the principal mechanism for ionization of neutrals (expect Na and K) and the dominant source of ions accelerated to corotation, the primary mode of multiply charge ion recombination, and a major contributor to mass loss via fast neutrals. As a consequence, the ratios of ion concentrations are critically dependent on charge-exchange rates and the neutral densities. Charge-exchange reactions of torus ions with molecular species of Io's exosphere may yield a net supply of neutrals and plasma to the Io torus. Expressions are given to obtain the velocity dependence of the charge-exchange cross sections and to calculate cross sections for reactions not considered here.