Rare earth Manganese Oxide (ReMO) is an ABO₃ type perovskite material that is a known oxygen storage material.  When used as the cathode in a cell with lithium metal acting as the anode, it showed battery behavior with capacities higher than that of commercial lithium manganese oxide .  In this work, we want to show  that the synthesis method and post-treatment of the resulting perovskite effects both it's chemical composition and the physical structure. We concluded that the nature of the chemical composition or structure has a direct relationship to the mechanism of the battery function.  By using multi-scan cyclic voltametry in combination with in-situ electrochemical atomic force and scanning tunneling microscopy along with ex-situ synchrotron XAS and XRD we were able to clearly understand the cathode mechanism.