Various energy devices with enhanced performance can be fabricated based on nanostructured carbons and conducting polymeric electrolytes. For instance, supercapacitors are attractive energy storage devices due to their high power density. In the present work, supercapacitors are fabricated using synthesized carbon aerogel as an active electrode in combination with different electrolytes. Electrolytes are important components in supercapacitors since their electrochemical properties directly influence the performance and the internal resistance of the capacitor. Aqueous electrolytes of KOH, H2SO4, H3PO4 and six different gel electrolytes PVA/KCL, PVA/H3PO4, PVA/H2SO4, PVA/KOH, and PVA/KOH–KCl–K3[Fe(CN)6] and PVA/KNO3 are used for making flexible supercapacitors. The electrochemical properties of the different electrolytes are compared using cyclic voltammetry, galvanostatic charge/discharge curves and impedance spectroscopy. The capacitor containing PVA–KOH–KCl–K3[Fe(CN)6] electrolyte membrane with a weight ratio of 60:23:23:4 shows the highest specific capacitance of 520 F g−1 and a long cycling life with retention of 98.1% after 1000 cycles, also its specific capacitance increases with increasing the temperature from 25 to 70 °C.