In this work, the tin oxide/carbon nanotubes (SnO2/CNT) nanocomposite, where SnO2 nanoparticles were deposited on the functionalized single wall CNTs, has been shown to exhibit desirable electrochemical performances as the negative electrodes for the lithium ion batteries. CNTs not only suppressed the mechanical degradation of SnO2 and therefore provided the composite electrode with excellent capacity retention (>650 mAh g−1 with less than 10% capacity loss after 100 cycles), but also enhanced the electronic conductivity of the electrodes leading to excellent rate capability. The nanostructure of the nanocomposite has been shown to be critical for mitigating the mechanical degradation of electrodes.