Nitrogen-containing mesoporous carbons were obtained by co-pyrolyzing gelatin and magnesium citrate between 600 and 900 °C. The presence of magnesium citrate lowers the carbonization temperature and its decomposition product, MgO, works as a template for mesoporous carbon. Fourier-transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopic studies indicate that the nitrogen in the material exists in the form of pyridinic, pyrrolic and oxidized nitrogen. With high specific surface area, homogeneous pore-size distribution and abundant active sites at the edge of the graphene layer, the pyrolytic carbon shows very high reversible sodium (Na) storage capacities up to 360 mA h g⁻¹ and stable cycling stability.