The lithium insertion characteristics of lithium vanadate, Li4V3O8, were investigated using LiV3O8 prepared by the precipitation technique as the starting material. The Li4V3O8 phase was formed by lithiation over x = 1.5 in Li1-xV3O8, and the diffusion of lithium in this phase determined the reaction rate of insertion more than x = 1.5. Improvement of insertion kinetics in the Li4V3O8 phase extended the lithium insertion Limit from x = 3.2 to x = 4.0, compared with the case of LiV3O8 by conventional high temperature synthesis. Lithium insertion proceeds as the single-phase reaction in the range of 3.2 < x < 4.0.