A decreasing in the amounts of phenolic compounds, which mayinclude phenol, vanillin, vanillic acid, coumaric acid, syringalde-hyde [23], was observed in the treatment with the two types ofcharcoal used. However, the reduction of these compounds inCABH-4 was of 63.2%, while in CABH-3 was of only 28.3%, showing that the use of the charcoal with lower particle size was more efficient, since it has a larger surface area of contact. The most suitable detoxification process to improve fermentation of hemicellulose hydrolysates depends on its very nature; the ideal method should eliminate the greatest amount of toxic compounds and cause thelowest loss of fermentable sugars. However, to achieve an efficient fermentation, once the process parameters have been evaluated,it must be defined whether it is necessary a total or a partial