Particulate MnO₂, having simultaneously a micropore surface area greater than 8.0 m²/g, desirably between about 8.0 and 13 m²/g and BET surface area of between about 20 and 31 m²/g within the context of an MnO₂ having a total intraparticle porosity of between about 0.035 cm³/g and 0.06 cm³/g produces enhanced performance when employed as cathode active material in an electrochemical cell, particularly an alkaline cell. The average pore radius of the meso and macro pores within the MnO₂ (meso-macro pore radius) is desirably greater than 32 Angstrom.