The development of low-cost, high-performance, nonprecious-metal electrocatalysts for the oxygen reduction reaction (ORR) is highly desirable to reduce the cost of fuel systems. Self-supported nitrogen-doped carbons containing cobalt have been developed by electrospinning followed by pyrolysis treatment. Polyacrylonitrile (PAN) with abundant carbon and nitrogen sources serves as a polymer in the fabrication of one-dimensional nanofibers by electrospinning. After being calcined at various temperatures, the obtained nitrogen-doped carbon nanofiber encapsulating cobalt nanoparticles at 800 degrees C (Co-PAN-800) exhibits the highest ORR activity with onset and half-wave potentials of -0.02 and -0.092V (vs. Hg/HgO) in 0.1m KOH, respectively. Additionally, the optimal Co-PAN-800 material shows remarkable stability and strong tolerance against methanol crossover. The promising ORR performance of Co-PAN-800 is attributed to the high surface area (407.43m(2)g(-1)), which ensures sufficient exposure of electrocatalytically active sites. XPS analysis further demonstrates that pyrrolic nitrogen and a highly graphitized carbon structure may be responsible for the enhanced ORR activity of Co-PAN-800; cobalt may be involved in the creation of pyrrolic nitrogen during pyrolysis treatment.