The interaction of CpMoH(CO) 2 (PMe 3 ), 1, with AgBF 4 in acetonitrile establishes an equilibrium (K ) 9 ( 1) with the hydride-bridged adduct [Cp(CO) 2 (PMe 3 )Mo(µ-H)Ag(MeCN) x ]-BF 4 , 4, which is in a fast chemical exchange on the NMR time scale with compound 1. The interaction of 1 and AgBF 4 in THF leads to the formation of the trinuclear complex {[CpMoH-(CO) 2 (PMe 3 )] 2 Ag}BF 4 , 5, as an insoluble white solid in 73% yield when the Mo/Ag ratio is 2:1. The nature of the precipitate does not depend on the relative stoichiometry of the two reagents. When redissolved in acetonitrile, compound 5 dissociates, generating a mixture of 1 and 4. Compound 4 slowly evolves to the solvent adduct, [CpMo(CO) 2 (PMe 3 )(MeCN)]-BF 4 , 3, with elimination of hydrogen gas and metallic silver. The decomposition of 4 could be interpreted as either an inner-sphere electron transfer or a substitution of unstable "AgH".