Lithium insertion and extraction kinetics of lithium trivanadate, Li1+xV3O8, was investigated by using the electrochemical measurements at various temperatures and current densities. The results showed that the reaction rates of both insertion and extraction were limited by the small diffusivity of Li+ ions in the Li4V3O8 phase formed for x > 1.5 upon lithiation. Extraction reaction was also dependent on the thermodynamic factor on the basis of the incomplete reversibility of transformation from the Li4V3O8 phase to the original LiV3O8 one.