Manganese oxide/carbon powders have been prepared by reduction of acidic KMnO₄ by carbon. The influence of the type of carbon ［active carbon (AC), meso-carbon microbeads (MCMB), and flexible graphite (FG)］ as well as the presence of Ni²⁺, Co²⁺ or Er²⁺/Er³⁺ ions on the structure and electrochemical properties of the resulting manganese oxide/carbon powders was investigated. The structure and surface morphology of the manganese oxide/carbon powders were examined by X-ray diffraction and scanning electron microscopy. It was shown that AC has a higher reducing power than either FG or MCMB. Results of CV experiments showed that the manganese oxide/carbon powders possess excellent capacitive properties, with the specific capacitance measured by cyclic voltammograms reaching a maximum of 117F/g before doping. After doping with Ni²⁺ andCo²⁺ ions, the specific capacitance showed an increased value of 185F/g. 