Prior to realizing grid-scale applications of the energy storage devices, there remain several key issues including the development of low-cost, high-performance materials and electrolytes which are environmentally friendly and compatibles with low-temperature and large-scale processing. The present work reports the preparation, characterization, and comparative application of two PILs namely, diisoprpylethylammonium methanesulfonate, [DIPEA][MeSO3], and pyrrolidinium methanesulfonate, [Pyrr][MeSO3], in mixture with water as electrolyte for supercapacitor applications. Different electrochemical measurements like cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge were conducted to study the performance of these aqueous solutions as supercapacitors with activated carbon electrode. From this work, good specific capacitances up to 102Fg−1 have been observed even at high-rate cyclability, as well as an increase of the specific power close to 13.9kWkg−1 at high current density of 15Ag−1.