Biomimetic solid solutions of manganese and cobalt carbonates (MnCO(3)-CoCO(3)) are used as the precursors for the synthesis of the corresponding metal oxides. The different structures of the metal oxides with porous morphologies, such as pure manganese monoxide (MnO), the solid solution of manganese and cobalt monoxide (MnO-CoO), and the nanocomposite of MnO and metallic cobalt (MnO/Co), are obtained by the appropriate thermal treatments under a reduction atmosphere. The contents of cobalt species can be controlled by the initial cobalt concentration in the MnCO(3)-CoCO(3) precursors. The resultant MnO/Co nanocomposites show the enhanced charge-discharge cycle stability and rate performance as an anode material of lithium-ion battery.