epsilon-VOPO4 was synthesized from the monoclinic and tetragonal forms of H2VOPO4 by the electrochemical de-intercalation of the protons in both nonaqueous and aqueous electrolytes, as well as by the thermal decomposition of H2VOPO4. The epsilon-VOPO4 so formed readily and reversibly reacts with up to two lithium ions. The epsilon-VOPO4 from the tetragonal precursor has a reversible capacity exceeding 130 mAh/g on its higher voltage plateau, and even at a 2 mA/cm(2) cycling rate has a capacity of 95 mAh/g comparable to that of the spinel LiMn2O4. The electronic conductivity of the epsilon-VOPO4 is 1 x 10(-6) S.cm(-1) and the lithium chemical diffusion coefficients is in the range of 1 x 10(-11) to 5 x 10(-9) cm(2) s(-1) depending on composition. The structure changes little during hydrogen removal and lithium intercalation, and the changes are reversible. (c) 2005 The Electrochemical Society.