Based on inorganic fuel, an Ammonia-Oxidation Microbial Fuel Cell (AO-MFC) had been developed, and the influence and mechanism of dissolved oxygen (DO) on the performance of nitrification and electricity generation were investigated. The results showed that the maximum conversion percentage of ammonium nitrogen (NH4+-N) was 99.7%. The output voltage and the power density were 98.5 +/- 1.41 mV and 9.70 +/- 0.27 mW m(-2) in the stable phase of electricity generation. In the AO-MFC, the electrons originated from ammonia and flowed to ammonia monooxygenase (AMO, which catalyzes the conversion of ammonia to hydroxylamine), Cyt aa(3) oxidase (which catalyzes the reduction of oxygen) and electrode, which were used for triggering ammonia oxidation, synthesizing ATP and generating electricity. Molecular oxygen played a key role in the electron distribution among these three acceptors. DO concentration too high (>6.45 mg L-1) or too low (<0.5 mg L-1) could exert a great negative influence on the performance of electricity generation. Copyright (c) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.