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 102 F g(-1) have been observed even at high-rate cyclability, as well as an increase of the specific power close to 13.9 kW kg(-1) at high current density of 15 A g(-1). (C) 2012 Elsevier Ltd. All rights reserved.