Monoclinic/hexagonal mixed-phase LiMnBO3/C composites have been prepared by the impregnation-precipitation method using ketjen black (KB) with 3D conductive network as both template and conductive framework. The synthesized products are characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen sorption and electrochemical tests. Morphology studied by SEM and nitrogen sorption shows that LiMnBO3 particles are embedded in the nanostructured carbon networks. The LiMnBO3/C electrodes deliver an initial discharge specific capacity of 150, 137, 121 and 85 mAh g−1 at C/20, C/10, C/5 and C/2 rate, respectively. Although the capacity for the LiMnBO3/C electrode decreases considerably with increasing rate, stable cycling performance is obtained for all the four rates.