Starting from waste polytetrafluoroethylene (PTFE), metal oxides (TiO2, V2O5, Nb2O5, and MoO3) and metal sodium, several nanocrystalline transition metal carbides (TiC, VC, NbC, and Mo2C) have been prepared through a thermal reduction route in an autoclave at 600 degrees C. It is found that the obtained NbC nanocrystallines have a superconducting transition temperature at 11.6 K. (C) 2012 Elsevier B.V. All rights reserved.