In this book we present the performance of dry cells containing electrolytic MnO2, natural MnO2, or a mixture of both. Both components have been characterized by chemical analysis. Continuous discharge tests performed on EMD-based dry cells show a much longer discharge time than that of pure NMD; however, batteries containing a mixture show intermediate discharge time values. The value of the diffusion coefficient estimated by GITT or impedance spectroscopy shows that the H+ diffuses faster in the EMD variety than in the NMD variety.