Co3O4 nanoparticles are prepared via converting cobalt oxide subunits in a cobalt metal-organic framework (Co-3(NDC)(3)(DMF)(4), NDC=2,6-naphthalene- dicarboxylate; DMF = N,N'-dimethylformamide) by pyrolysis in air. The as-prepared Co3O4 shows an agglomerated secondary structure with an average diameter of around 250 nm comprised of small primary Co3O4 particles with a size of about 25 nm. This agglomerated structure favors the enhanced capacity, improved rate capability and prolonged cycle life as an electrode material for lithium ion batteries. (C) 2009 Elsevier B.V. All rights reserved.