NiO/Ni nanocomposite is in situ prepared by a facile citric–nitrate method. The as-prepared NiO/Ni powders show uniformly distributed particle size of ca. 30–40 nm. The prepared NiO/Ni composite shows high reversible capacity, excellent cycling stability, and superior rate capability, with a specific capacity of ca. 800 mAh g−1 maintained at a current density of 0.1C after 50 cycles. Even at a high current density of 5C (3.59 A g−1), the electrode still exhibits a reversible capacity of 450 mAh g−1. Moreover, the synthesized NiO/Ni composite displays a superior electrochemical performance at high temperature (50 °C), with a reversible capacity of 635 mAh g−1 for 300 cycles at 2C. The preparation method is facile and can be extended for other transition metal oxides for the development of high performance lithium ion batteries.