Electrochemical characteristics of m-dinitrobenzene (m-DNB) based composite cathode materials involving compounds such as AgCl, TiO2, HgO and CuCl have been investigated and (Mg AZ31 alloy anode) as an activated battery system using 2 M magnesium perchlorate aqueous electrolyte. The concentration of the composites has been optimized so as to obtain high electrochemical performance of Mg/m-DNB reserve batteries through constant current discharge studies. Mg/m-DNB cells containing 5-wt % of HgO when discharged at current density of 2.1 mA cm(-2) delivered 5.3 Ah capacity corresponds to a columbic efficiency of 97% as compared to the cells without composite.