(copyright) 2021 Science PressAn eco-friendly, new, and controllable approach for the preparation of manganese oxide (alpha-MnO2) nanorods has been introduced using hydrothermal reaction for supercapacitor application. The in-depth crystal structure analysis of alpha-MnO2 is analyzed by X-ray Rietveld refinement by using FullProf program with the help of pseudo-Voigt profile function. The developed alpha-MnO2 electrode attains a remarkable capacitance of 577.7 F/g recorded at a current density value of 1 A/g with an excellent cycle life when is used for 10,000 repeated cycles due to the porous nanorod-morphology assisting the ease penetration of electrolyte ions into the electroactive sites. The diffusive and capacitive contributions of the electrode have been estimated by considering standard numerical packages in Python. After successfully assembling the aqueous symmetric supercapacitor (SSC) cell by utilizing the as-prepared alpha-MnO2, an excellent capacitance of 163.5 F/g and energy density of 58.1 Wh/kg at the constant current density of 0.5 A/g are obtained with an expanded potential frame of 1.6 V. Moreover, the cell has exceptionally withstood up to 10,000 cycles with an ultimate capacitance retention of 94.1% including the ability to light an LED for 18 s. Such findings recommend the developed alpha-MnO2 electrode to be a highly felicitous electrode for the field of energy storage.