Eight kinds of amino acids including L-Serine (Ser), L-Asparagine (Asn), L-Asparticacid (Asp), L-Glutamicacid (Glu), DL-Alanine (Ala), L-lysine (Lys), L-Histidine (His) and L-Arginine (Arg) are tested as substrates of single-chambered air-cathode microbial fuel cells (MFCs) with domestic wastewater as inoculation. Their total organic carbon (TOC) concentrations in solution are standardized as 720 mg L (1). Ser produces the highest power density of 768 mW m (2) and Ala produces the lowest of 556 mW m (2). The Coulombic efficiencies (CEs) vary from 13 +/- 3% (obtained with Arg) to 30 +/- 1% (obtained with Ala). The removal efficiencies of total nitrogen (TN) are from 55 +/- 5% (Asn) to 94 +/- 4% (Asp), which may be associated with CEs. Maximum voltage outputs and TOC concentrations of the substrates appear to satisfy the empirical Monod-type equation when the external resistance is 150 Omega. The performances of MFCs are considered to relate to the molecular weights and structures of eight amino acids. (C) 2012 Elsevier Ltd. All rights reserved.