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.