A hollandite-type manganese dioxide (HoIMO), without foreign metal cations (K+, NH4+, Na+) in the (2 x 2) tunnel, was prepared directly by reacting LiMnO4 with Mn(NO3)2 in an H2SO4 acidic solution. The HoIMO belonged to a body-centered tetragonal system (space group 14/m) and could be expressed by the formula H4xMn8-xO16 . yH2O. A preliminary electrochemical study suggested that the HoIMO is promising as the cathode for a lithium rechargeable battery.