Three different types of catalysts were evaluated for organosolv pretreatment with pitch pine (Anus rigida) Sulfuric acid, magnesium chloride, and sodium hydroxide for acid, neutral and base catalysts, respectively, were used, and ethanol was the organic solvent The pretreatment process was conducted at different temperatures and times. The enzymatic hydrolysis process followed to estimate the digestibility of the biomass The digestibility of pitch pine by pretreatment process with 1% sulfuric acid at the optimal condition was approximately 55-60%, and that by 1% magnesium chloride was nearly 60% The pretreatment with 1% sodium hydroxide had no effect on digestibility at 10%, but the digestibility improved by more than 80% when the concentration was increased to 2% Theoretical ethanol yield was the highest at organosolv pretreatment with sulfuric acid at 70% and the lowest with sodium hydroxide at 45% (C) 2010 Elsevier Ltd All rights reserved.