Layer-controllable CoO and Co3O4 platelets were prepared by calcination of hexagonal beta-Co(OH)(2), which was synthesized via a surfactant-free hydrothermal method. As negative electrode material for lithium-ion batteries, CoO and Co3O4 platelets demonstrated high reversible capacity (more than 800 mAh/g for CoO and 600 mAh/g for Co3O4) and excellent electrochemical cycling stability. The multilayered CoO platelets showed larger capacity and much better cycling performance than the monolayer CoO platelets and CoO nanoparticles. The effect of dimension and morphology of CoO particles on the electrode behavior was discussed. (c) 2008 The Electrochemical Society. [DOI:10.1149/1.2987945] All rights reserved.