Carbon derived from chitosan, followed by phosphoric acid activation during thermal treatment to obtain N and P dual-doped catalyst, is studied as the catalyst for air-cathode in a microbial fuel cell (MFC). The maximum power density (MPD) of 1603.6 +/- 80 mW m(-2) is achieved, which is 5 times as high as that of the control (322.4 +/- 16 mW m(-2)) when N, P-codoped carbon was calcined at 850 degrees C. The better performance is due to a higher open circuit potential, lower total resistance and higher exchange current density. In addition, the optimized catalyst possessed the largest specific surface area of 982.18 m(2) g(-1), so it could transfer more oxygen and supplied added active sites. And the existence of graphitic nitrogen, phosphorus and high content of carbon oxygen bonds promoted the cathode performance in MFC. In brief, the N and P dual-doped carbon from chitosan was potentially low-cost catalyst for the high performance of MFC.