The electrochemical properties of amorphous vanadium pentoxide (V2O5) thin films deposited by reactive r.f.-sputtering were investigated using galvanostatic charge/discharge cycling and galvanostatic intermittent titration technique (GITT). As x in Li (x) V2O5-y increased (x = 0-2.0), the electromotive force of the lithium (Li)a 1 pound M LiClO4-propylene carbonatea Li pound (x) V2O5-y cell decreased gradually without a potential plateau or an abrupt potential reduction, demonstrating that an irreversible structural change did not occur in the entire Li content. Chemical diffusivity of the Li ion in the Li (x) V2O5-y thin film measured using GITT was determined to be 4 x 10(-13)-7 x 10(-14) cm(2) s(-1) in the Li content range investigated.