Nanostructured SnO2 and SnO2-graphite composites were prepared by microemulsion synthesis using Tergitol 15-S-5 as the surfactant. The size of the SnO2 nanoparticles was typically between 15 and 20 nm. The graphite-SnO2 composite containing 9.8 wt % SnO2 showed a high reversible Li+ storage capacity of 384 mAh/g which decreased by only 4% in 30 cycles. The substantial cyclability improvement relative to unsupported SnO2 is believed to be due to the uniform dispersion of the SnO2 nanoparticles on the graphite surface, which reduces particle aggregation during Li+ insertion and extraction reactions. (C) 2002 The Electrochemical Society.