Silver vanadium phosphorous oxides (SVPO) have been recently shown to be a promising new class of materials for primary lithium batteries with the synthesis and electrochemical investigation of Ag2VO2PO4. More recently a second silver vanadium phosphorous oxide, Ag0.48VOPO4 center dot 1.9H(2)O, was reported. The investigation reported here provides mechanistic information regarding the reduction mechanism of Ag0.48VOPO4 center dot 1.9H(2)O via magnetic susceptibility measurements, quantitative XRD, and the use of galvanostatic intermittent titration (GITT) type tests. Ag0.48VOPO4 center dot 1.9H(2)O shows promise as a cathode material for primary cell applications demanding high voltage, state of charge indication, and good pulse performance such as biomedical battery applications. Additionally, the first exploration of electrochemical reversibility of a silver vanadium phosphorous oxide material is reported. Via slow scan voltammetry and ex-situ XRD of both discharged and charged material, Ag0.48VOPO4 center dot 1.9H(2)O shows reversibility of the vanadium center however, little reincorporation of the silver metal produced during the discharge is observed during the charge step. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.062210jes] All rights reserved.