Two-dimensional (2D) nanosheets directly grew into three-dimensional (3D) microspheres through a one-step solvothermal route under controlled conditions; during this procedure the decomposition of hexamethylenetetramine at temperatures higher than 120 °C provided OH− at the rate of good diffusion, and surfactants were used as templates to provide the growth sites and control the crystalline growth direction. By means of the Ostwald ripening process, precursor microspheres formed with narrowly distributed diameters, and then NiO 3D microspheres were obtained with further calcination at 300 °C for 2 h. NiO microspheres presented a high initial discharge capacity as anode materials in Li ion batteries, but degraded quickly during subsequent cycles, and further improvement in cyclic stability is still needed for practical application in Li ion batteries.