Ag1+xV3O8 has been prepared by the ion exchange reaction in the molten salt of AgNO3 using Na1.2V3O8. This oxide has a similar layer structure to M1+xV3O8 (M = Li and Na), and its lattice parameter has been determined. Up to four moles of lithium (x = 4) in LixAg1.2V3O8 are accommodated electrochemically. The discharge process showed that after deposition of metallic silver by reduction of Ag(I) prior to V(V) and simultaneous occupation of the octahedral site by inserted Li(I), additional lithium was inserted into Li1.2V3O8. The charging process showed extraction of three lithiums from Li4V3O8 and no return of the silver element back to the original structure with oxidation.