This study explored a new approach to the pretreatment of lignocellulosic biomass using FeCl3 combined with a fuel cell system to generate electricity. After pretreatment, ferric iron (Fe3+), a strong catalyst in the hydrolysis of carbohydrate, was found to be reduced to ferrous iron (Fe2+) by means of the oxidation of xylose and lignin. Ferrous iron, as a fuel, was employed to the anode part of a fuel cell, generating power of 1110 mW/m(2). During the fuel cell operation, ferrous iron was completely removed through oxidation to ferric iron and precipitated out. The optimal conditions for the operation of the fuel cell were found to be a pH of 7.0 and ferrous iron concentration of above 0.008 M. These results clearly show that a fuel cell system could be used not only to remove ferrous iron from liquid hydrolysate, but also to produce electricity. (C) 2012 Elsevier Ltd. All rights reserved.