The electrochemical intercalation of lithium into chromium (V)-containing oxides isostructural with beta- and gamma-Li3PO4 has been studied. beta-Li3CrO4 can reversibly intercalate around 1 mole of Li ions per formula unit to give Li3+xCrO4:0 < x < 1 with a discharge capacity of 196 mAh g-L; electrochemical data indicate the possible existence of a two-phase region in the approximate range 0.3 gamma transition, the orthorhombic c axis, and the unit cell volume, increase by similar to 2%.