This paper presents the direct synthesis of highly nanoporous carbon materials via the carbonization of sodium oxalate in inert atmosphere without any activation. The carbonization temperature and time are very important for the carbon structures and their electrochemical performance in supercapacitors. The SOC–800–2.5 material derived from sodium oxalate has a high specific surface area of 1456 m2 g−1, and a total of 74 % of the pore volume is composed of mesoporosity with average pore size 3.7 nm, which is ideal for adoption as an electrode for supercapacitors. The SOC–800–2.5 material can also deliver a high specific capacitance of 245 F g−1 at a constant charge/discharge current of 0.7 A g−1. This capacitance is maintained at a value of 173 F g−1 at 10 A g−1. This material also has good cycle stability with over 89.1 % capacitance retention after 5000 cycles when measured in a three-electrode system using 6 M KOH as electrolyte.