Background and purpose: For application in supercapacitors, improving the efficiency of the electrode materials is the most important for obtaining high performance. Porous carbon with suitable architectures is reliable for improved electrochemical capacitors. In this study, we optimized the maize cobs as a potential abundant precursor for the production of porous carbon supercapacitor applications. This research study aimed to advance on the activation method for Activation of the biomass and to up-cycling agricultural biomass into carbon-based porous materials for supercapacitor electrode application. The carbonized samples were kept in a desiccator for 3 hours to allow intercalation and interaction of the carbon lattice expansion by K+ ion before Activation [Topic, RQ]. Results: The physical and chemical characterization of the synthesized materials was carried out several techniques for determining different properties of the activated carbon from maize cobs, including; structural-functional groups, morphology, chemical composition, physical properties and electrochemical performance. The results revealed surface structure with oxygen-based functional groups carried by XPS and FTIR, the amorphous nature by XRD, high-temperature stability to degradation by TGA/DSC, among others. Also, the structural characterization revealed a BET specific surface area of 1443.94 m2/g with a pore volume of 0.7915cm3/g. Symmetric devices based on the produced materials delivered a specific capacitance of 358.7F/g with an energy density of 12.45 Wh/kg and a corresponding power density of 250 W/kg at 0.5A/g [Outcome]. Conclusions: The as-prepared electrodes exhibited excellent stability with the capacitance retention of 99% at the maximum potential for a repeated 10hr to a total of 130 h. The industries can commercialise these activated carbon materials for application in energy storage systems and water purification due to their porosity and high-temperature resistance to degradation [Contributions].