Using interlaced carbon nanotubes (CNTs) as framework, a novel three-dimensional (3D) networks structured Co(NO3)2·6H2O@CNTs with superior electrochemical performance is synthesized by an ultrasonic assisted hydrothermal and low-temperature conversion method. In the micro-/nanostructured composite, Co(NO3)2·6H2O particles, with an average size about 0.7μm, are homogeneously embedded in the CNTs 3D networks. The CNTs, with high electronic conductivity and outstanding mechanical flexibility, are effective to keep the stability of Co(NO3)2·6H2O micro-/nanostructures. Evaluated as anode material for lithium ion batteries, the micro-/nanostructured Co(NO3)2·6H2O@CNTs exhibits a high reversible capacity of 1460mAhg−1 at a current density of 50mAg−1 after 100 charge/discharge cycles. Even at 1000mAg−1, a superior stable capacity as high as 1089mAhg−1 could be maintained after 1000cycles. The improved reversible capacity, excellent cycling stability, and good rate capability of Co(NO3)2·6H2O@CNTs can be ascribed to the three dimensional structure and the synergistic effect between Co(NO3)2·6H2O and CNTs. Therefore, this Co(NO3)2·6H2O@CNTs micro-/nanocomposite can be considered as an attractive anode candidate in rechargeable lithium ion batteries.