Pretreatment of lignocellulosic biomass using dilute sulfuric acid treatment is carried out at high temperature (121°C for 1 hour). During this process some of the sugars released from biomass react and form chemicals that are inhibitory for cell growth or fermentation, or both. Pichia stipitis, a natural pentose-fermenting yeast, is inhibited by compounds produced during pretreatment and hydrolysis of lignocellulosic biomass (Slininger et al. 2009). Examples of some of these inhibitors include furfural, hydroxymethyl furfural, acids (acetic, ferulic, gluc­uronic, vanillic, syringic, and p-coumaric), and other chemicals such as vanillin and syrin — galdehyde (Tran and Chambers 1985; Grohmann and Bothast 1997; Ezeji et al. 2007a). To be able to ferment toxic hydrolysates to ethanol or butanol a number of detoxifying methods exist such as treatment with Ca(OH)2 (also called overliming), use of XAD resins (Sigma Chemicals, St. Louis, MO), or use of cultures that can metabolize the inhibitors. Studies on developing such inhibitor-metabolizing strains (Coniochaeta ligniaria) have been successful (Nichols et al. 2008). However, inhibitor utilization has to be carried out before the produc­tion of ethanol when using hexose — and pentose-fermenting strains. Another alternate could be the development of cultures that can tolerate and utilize inhibitors and still produce ethanol or butanol. In an interesting approach, acidic and alkaline-electrolyzed water was used to hydrolyze agricultural biomass and produce biofuel without any significant inhibitory effects on the microbial cultures (Wang et al. 2009). However, a much lower sugar yield was obtained when employing these approaches than when using dilute H2SO4.