In this study, MnO² with different nanostructures (nanorods, nanospheres, nanoflowers, nanolychee) were obtained using a facile chemical method by adding different amounts of sulfuric acid for application in supercapacitors. Structure, morphology and composition were examined by X-ray diffractometer, Brunauer-Emmett-Teller, Fourier transform infrared, etc. Electrochemistry performances were tested by Autolab and LANHE CT2001A test system. Results indicated that the nanoflower MnO² (F-MnO²) exhibited largest specific surface area, which was 83.17 m² g-1. Electrode materials were tested in different electrolytes, including 6.0 M KOH, 1.0 M LiNO₃ and 1.0 M LiOH. The F-MnO² electrode material displayed the best electrochemical properties, and its specific capacitance was 171 F g-1 at 1 A g-1. Moreover, F-MnO² electrode material showed splendid cycling durability was 130.9% of original value after 1000 cycles. These results demonstrated that the F-MnO² electrode material should be a promising candidate for application in supercapacitors.