Electricity generation using microbial fuel cells ( MFCs) was examined from corn stover waste biomass using samples prepared through either neutral or acid steam- exploded hydrolysis processes that convert the hemicellulose to soluble sugars. Maximum power densities in fed- batch tests using an air-cathode MFC were 371 +/- 13 mW/m(2) and 367 +/- 13 mW/m(2) for the neutral and acid hydrolysates ( 1000 mg- COD/ L, 250 Omega). Power output exhibited saturation kinetics with respect to fuel concentration, with predicted maximum power densities of P-max) 475 mW/ m(2) and half- saturation constants of K-s) 347 mg/ L ( neutral) and Pmax) 422 mW/m(2) and Ks) 170 mg/ L ( acid). Coulombic efficiencies ( CEs) were comparable to that found using carbohydrates in this type of MFC, with values ranging from 20 to 30% for both hydrolysates. All sugars ( monomeric or oligomeric) were completely utilized, with overall biochemical oxygen demand ( BOD) removal efficiencies of 93 +/-2% ( neutral) and 94 +/- 1% ( acid). Power output could be increased by using a cathode containing a diffusion layer, resulting in maximum power densities of 810 ( 3 mW/m(2) ( neutral) and 861 ( 37 mW/m(2) ( acid). Power was further increased by increasing solution conductivity to 20 mS/ cm, resulting in 933 mW/ m(2) ( neutral) and 971 mW/ m(2) ( acid) for the two hydrolysates. Additional increases in solution conductivity lowered the anode potential and did not increase power. These results demonstrate the potential for a new method of renewable energy production based on conversion of biomass to electricity using MFCs.