Manganese oxides have a long history of serving as a cathode in charge storage applications. Electrolytic manganese dioxide (EMD) is widely used in alkaline batteries and MnO2 originally was part of the Leclanché wet cell patented in 1866. Leclanché wet cells used a naturally occurring MnO2 ore with Zn metal as anode and ammonium chloride electrolyte. While there are a vast number of topics to discuss on manganese oxides, in this short paper, two topics researched at Argonne over the last 12 years are highlighted. First, the addition of lithia (Li2O) as a stabilizing component in 3V alpha-MnO2 is examined. Second, an overview of the evolution of layered–layered composite-structured electrodes derived from the lithium-manganese oxide (Li2MnO3) layered rock-salt phase is presented.