3D N-doped carbonized bacterial cellulose (NCBC) networks are successfully prepared through carbonizing a bacterial cellulose (BC) and urea mixture. The resultant optimized NCBC samples obtained at 800 degrees C (NCBC-800) are used as electrocatalysts for oxygen reduction reaction (ORR). NCBC-800 exhibits superior electrocatalytic activity with a relative positive onset potential of -0.168V (vs. Ag/AgCl). Notably, the NCBC-800 electrocatalyst presents a dominant 4-electron pathway in ORR and extremely high durability with nearly 100% activity retention after 20000 s continuous tests.