An effective method is proposed for improving energy generation of microbial fuel cells (MFCs) by using nitric oxide (NO) and oxygen (O-2) as electron acceptors for the first time. This new MFC based on the binary gas (BGMFC) shows apparently higher power output than MFC using single gas (NO or O-2) as electron acceptor (SGMFC). BGMFC (NO: 1%, O-2: 20%) shows a cell voltage as high as 820 mV (external resistance: 1000 Omega), and its current density is 1.5 times that of SGMFC (O-2: 20%). The maximum power density of BGMFC is 1227 +/- 45 mW m(-2), which is 73% higher than that of SGMFC (710 +/- 42 mW m(-2)). The power generation of BGMFC goes up obviously when increasing the NO concentration in the presence of O-2. The coexistence of NO and O-2 is found to be essential, and when single NO is used at cathode, the power output drops down rather than increases. The possible cathodic reaction pathway of BGMFC is discussed. A slight decrease is observed in the pH of the electrolyte, whose effect on the power output is negligible. The catalysis of NO and its reduction intermediate is believed to be critical for the good performance of BGMFC.