A process was developed to produce electrolytic manganese dioxide, suitable for use in high quality dry cells, from Risdon anode mud. ImpurItIes present In the anode mud were removed prior to the electrolysis which was performed from a manganese sulphate bath using the following conditions.Temp. 95CH2S04 50-55 g/l.Mn2+ 55-60 g/l.Anode c.d. 100 A/sq. ft.Operation under these conditions yielded current efficiency and power consumption figures of 95 per cent and 08 kWh/lb respectively. The product conformed to battery manufacturers' specifications as regards physical and chemical properties and performed satisfactorily in a battery testing programme.