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In this study, different surface morphologies of MnO$_2$ (rod, wire, urchin and tube-like MnO$_2$) with an $\alpha$-phase crystalline structure were synthesized via a hydrothermal process by adding various reagents. The crystalline structure and morphology were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. In addition, the electrochemical properties were measured using cyclic voltammetry (CV) and galvanostatic charge/discharge (C.D.) in 1 M Na$_2$SO$_4$ aqueous solution. The specific capacitance of rod, wire, urchin and tube-like MnO$_2$ were about 110.20, 73.49, 53.80 and 64.31 F g$^-$$^1$. Especially, the rod-like MnO$_2$ exhibits a highest capacitance of 110.2 F g$^-$$^1$ at the current density of 0.5 A g$^-$$^1$ due to its smallest size.
