Herein, we have synthesized niobium carbide/carbon (NbC/C) nanocomposites by a magnesium-thermal reduction process at 600 degrees C in a stainless-steel autoclave. X-ray diffraction patterns indicate that the obtained product is cubic phase NbC with the calculated lattice constant a = 3.1170 angstrom. The obtained product shows an onset superconducting temperature at 11.4 K, which is similar to that reported for bulk NbC. In addition, the obtained product was also studied by thermogravimetric analysis (TGA). It had good oxidation resistance below 380 degrees C in air.