Gas-phase collision-induced dissociation of the Ag+-proline complex shows six major product ions. Tandem mass spectrometry reveals that at least three of the fragment ions are formed directly from the complex. These are a cyclic immonium ion, formed after elimination of AgH from the Ag+-proline complex, another cyclic immonium ion formed after the elimination of both AgH and CO2, and finally an ion formed as the product of a reductive-elimination reaction in which H-2 is lost as a neutral. Selective and nonselective deuterium labeling experiments and hybrid density functional calculations have been employed to probe fragmentation mechanisms that account for all experimental results. The mechanisms for the competitive losses of AgH and H-2 from the Ag+-proline complex have been calculated at B3LYP/DZVP.