Display omitted •Bamboo-leaf activated carbon was synthesized by chemical reaction method.•Bamboo-leaf AC is analyzed using various aqueous electrolyte solutions.•AC delivers a high capacity of CP 290F/g at 1A/g using mixed electrolytes.•Good cyclic stability around 1000 cycles with 93% capacity retention. Activated carbon (AC) material has been prepared from bamboo-leaf carbonized under high temperature at 500 °C for 2hr. Then, the chemical reaction method was processed on carbon material to activate using KOH solvent as activating agent. XRD and FT-Raman have confirmed the crystal structure and molecule interaction of the prepared activated carbon. The morphology was characterized using FE-SEM (EDS). The novelty of activated carbon was studied by various aqueous electrolyte such as 1 M Na2SO4, 0.5 M KOH and 1 M Na2SO4 + 0.5 M KOH. The activated carbon delivers the high specific capacitance found as 290F/g at 1A/g using mixed electrolyte (1 M Na2SO4 + 0.5 M KOH). In addition, capacity retention was achieved 93% after 1000 cycles at 10A/g. Mixed electrolytes can be used as a promising electrode material for supercapacitors with high power density.