The performance of symmetric supercapacitors with activated carbon electrodes, obtained from cellulose acetate microspheres as a precursor, has been studied using neutral aqueous sodium sulphate solutions as electrolytes. Although water-based electrolytes can safely operate in a broad temperature range, studies of supercapacitors beyond conventional room temperature conditions are rather limited, while most of investigations are focused on ionic liquids as electrolytes. However, since water represents a cheap, easy to handle and environmentally friendly solvent, detailed temperature investigations of supercapacitors with aqueous electrolytes are of importance. In the present work, we evaluated the behaviour of supercapacitors with electrolytes having various Na2SO4 concentrations, in a temperature range between 0 °C and 60 °C. Since stable and safe operation of supercapacitors with carbon electrodes exclusively depends on the electrolyte properties at these non-ambient conditions, the electrolytes were characterized with regard to their conductivity and viscosity at various temperatures. Activated carbon materials were produced by a one-step carbonization procedure of home-made cellulose acetate microspheres (CAM) using KOH as an activator, which was added to cellulose acetate microspheres in form of a solution for better homogenization. Supercapacitors with a neutral 1 M Na2SO4 solution as the best electrolyte composition were tested between 0 °C and 60 °C and provided specific capacitances between 91 F g−1 and 117 F g−1, demonstrating a good cycling stability with a retention of at least 95 % of the initial capacitance over 2000 cycles. Energy densities of 16.6 Wh kg−1 at a power density of 16 kW kg−1 are provided at 25 °C, whereas the energy density is improved at 60 °C to 21.5 Wh kg−1 at a slightly lower power density of 13.7 kW kg−1. No sign of electrochemical corrosion of battery housings was observed after cycling, in contrast to acid-based electrolytes with H2SO4 tested for comparison.