The air cathode fuel cell approach is promising for ferrous (Fe-ll) ion removal from acid mine drainage because iron and electricity are simultaneously recovered in the treating process. Here we show that electricity generation from Fe-ll can be enhanced by amending chelating anions to facilitate Fell oxidation at the anode of the fuel cell. A series of Fe-ll-fed fuel cells were operated with various chelating anions, including carboxylate, phosphate, and borate ligands. The average power densities of these fuel cells varied over a wide range from 0.08 +/- 0.5 to 107.85 +/- 1.50 mW m(-2). Citrate-amended fuel cells operated at pH 8-9 and carbonate-amended fuel cells operated at pH 6-8 exhibited greater charge-recovery efficiencies than others, which ranged from 93.5% to 96.1%. The redox potential of an anodic solution and redox activity of Fen were two important factors affecting the electrooxidation of Fe-ll in fuel cells.