We report the synthesis and characterization of the hollow micrometer-sized (Mn0.5Ni0.4Co0.1)CO3 precursor, and one of its promising lithium-enriched phases. The chemical composition of the resulting lithiated final material was Li1.2(Mn0.5Ni0.4Co0.1)O2+y . Lithium half cells with cathodes comprised of these hollow particles as the active intercalation material showed a reversible capacity of 183mAh/g when cycled between 2.0V and 4.6V. X-ray diffraction patterns and the electrochemical data of Li1.2(Mn0.5Ni0.4Co0.1)O2+y were consistent with the existence of the Li2MnO3-type integrated component that was activated during the initial charging of the cells. The results presented herein demonstrate a method to synthesize multicomponent, multiphase materials with hollow internal morphologies that can reversibly and stably be cycled with high gravimetric capacities as the active cathode material in lithium-ion batteries.