Nanoflower-like and nanoparticle spinel Li4Ti5O12 were synthesized by a microwave-assisted hydrothermal (MH) method following calcination. As-prepared Li4Ti5O12 was characterized by scanning electron microscopy, transmission electron microscopy, X-ray powder diffraction and cyclic voltammetry. The nanoflower-like and nanoparticle Li4Ti5O12 exhibited discharge capacities of 176.7 and 109.8mAhg−1, respectively, for the first cycle, and maintained reversible capacities of 138.4 and 91.7mAhg−1, respectively, at a 1.1 C-rate (200mAg−1) after 100 cycles. The better performance of nanoflower-like Li4Ti5O12 relative to nanoparticle Li4Ti5O12 is attributed to the larger specific surface area and shorter Li+ diffusion path of the former relative to the latter. The MH preparation process is straightforward and fast; thus it shows promise for widespread lithium ion battery applications.