Sn-doped Mn 3 O 4 /C nanocomposite was synthesized using Pluronics P123 (EO 20 PO 70 EO 20 ) as both structure-directing agent and carbon source. The phase and morphology was characterized with X-ray diffraction (XRD), X-ray spectroscopy (EDS), Field-emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The electrochemical performance of the sample was tested in 6M KOH A high specific capacitance of 216Fg −1 was achieved at current density of 5Ag −1 , and 93% capacitance retention remained after 10,000 charge/discharge cycles.