Mn3O4 nanoparticles anchored on continuous super-aligned carbon nanotube (SACNT) films are synthesized by decomposition of Mn(NO3)2. In the Mn3O4/SACNT composite electrodes, SACNT film is capable of serving as both the conductive pathway and structural scaffold, therefore no binder, extra conductive agent, or current collector is needed. The electrochemical performance of the Mn3O4/SACNT composite electrode is significantly affected by the particle size of Mn3O4. With smaller particle size, the electrode displays smaller voltage hysteresis and much improved reversibility and rate capability. The Mn3O4/SACNT electrodes with particle size of Mn3O4 less than 10 nm show a capacity retention of 95% after 100 cycles at 1 C and a high rate capacity of 342 mAh g−1 at 10 C (based on the total mass of the electrode), suggesting their advantages over the commercial graphite anode and potential in practical applications.