Akaline cell with improved cathode

A process is described whereby commercial manganese dioxide, for example, electrolytic manganese dioxide (EMD), is treated with ozone before it is utilized as cathode active material in an alkaline cell. The pretreatment of the manganese dioxide is accomplished by contacting manganese dioxide with ozone gas. Alternatively, the manganese dioxide may be treated with ozone while the cathode comprising said manganese dioxide is already in the cell casing. The treatment of the manganese dioxide improves the cell's open circuit voltage (OCV) and results in an increase in service life of the cell, particularly under high power application.