Reacting MnO₂, a lithium compound and a bismuth compound produces a lithium battery cathode material for lithium electrochemical systems. The same results can also be achieved by reacting MnO₂, lithium, or a compound containing lithium and bismuth, or a compound containing bismuth. Manganese based mixed metal oxides with lithium and bismuth were initially examined as a cathode material for rechargeable lithium and lithium-ion batteries in order to provide a new mixed metal oxide cathode material as the positive electrode in rechargeable lithium and lithium ion electrochemical cells. A stable mixed metal oxide was fabricated through a solid-state reaction between manganese dioxide, a lithium compound and bismuth or a bismuth compound. In addition to the lithium battery cathode material, a lithium manganese bismuth mixed metal oxide cathode, a lithium electrochemical system with a lithium manganese bismuth mixed metal oxide and a rechargeable lithium battery with a lithium manganese bismuth mixed metal oxide cathode are also provided. These devices provide much improved sustained specific capacity of about 120 mAhrs/g and the material exhibits an inherent catalytic behavior for charge transfer.