TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: The moisture is adjusted to 65-80 (preferably 70-80)% prior to continuous steam treatment. The mineral or organic acid is added to the biomass at 0.7-0.9 (preferably 0.8) wt.%. The biomass is steamed at atmospheric pressure for 10-60 minutes prior to subjecting the acidified biomass to steam treatment under pressure in a continuous treatment vessel. The process further comprises: drying the de-ethanolized slurry; and recovering energy from the pretreatment and drying steps. The amount of mineral acid added to the squeezed biomass is adjusted to achieve a pH of 1.8-2.5 (preferably 2) in the acidified biomass. The acidified biomass is pre-treated with steam in a continuous process vessel. The continuous pretreatment occurs at a pretreatment temperature of 130-180 (preferably 150-170) degrees C, and the pressure is above 100 psig. The pretreatment temperature is 160 degrees C for hardwoods and 150 degrees C for agricultural residues. The pretreatment time is 0.5-4 hours, preferably 45 minutes to hours. The pretreatment time is 45 minutes for hardwoods and 2 hours for agricultural residues. In the process, a severity index of the continuous pretreatment is 3.5-3.7, preferably 3.5-3.6. The continuous extraction comprises squeezing and/or water washing, either before or after explosive decomposition or both. The continuous extraction of the solid cellulose rich stream contains only 4-8 wt.% of xylose from remaining xylose, xylooligosaccharides and xylans. The continuous extraction is carried out at a pressure between atmospheric pressure and the pre-treatment pressure. The liquid stream extracted is concentrated by evaporation to a concentration of soluble solids 100-300 g/l. The extracted liquid stream is held at 90-125 degrees C for 1-3 hours. The extracted liquid stream is hydrolyzed in prior to being mixed back with the solids stream. In the process: energy required for concentrating is derived from recovered energy from the continuous pre-treatment; vapors created in the concentrating step from the evaporation of the soluble solids are recovered; and consistency of the solids stream obtained in step (i) is adjusted to 10-25%, consistency. The solids stream is adjusted 15% and 25%, preferably 17% consistency. The combined hydrolysate stream is co-fermented to ethanol with bacteria or yeast that converts both glucose and xylose to ethanol. The step of drying of the slurry takes place in a dryer for recovering heat as low pressure steam for use in other parts of the process such the distilling. The step (k) is carried out: at atmospheric pressure and a temperature of 98 degrees C; under a vacuum of 150 mba and a temperature of 80 degrees C; and a pressure of 20 psig. Preferred Components: The mineral acid is sulfuric acid, phosphoric acid, or sulfur dioxide. EXAMPLE - The lignocellulosic feedstock corncobs chopped to a size of 0.5-1 cm, was moistened with acidified water in a rotary mixer. The acidified, moistened cobs were conveyed to a batch steam gun in which the corncobs were pre-steamed for 30 minutes with directly injected steam at atmospheric pressure and the batch steam gun was sealed. Liquid condensate containing soluble corncob components was collected and drained continuously. The corncobs were pretreated and then diluted with fresh water in a ratio of 10:1 to form slurry. The slurry containing mainly cellulose and hemicellulose, were shredded and then diluted with fresh water to 17% consistency for hydrolysis and fermentation. The prehydrolysate solids stream obtained was subjected to enzymatic hydrolysis, to obtain a hydrolyzate stream. The liquid filtrate comprises xylose and other soluble sugars as well as soluble impurities. Concentrate the hemicellulose stream on a triple effect evaporator under vacuum conditions to achieve the desired concentrations. After concentration, prehydrolysate solids stream was hydrolyzed at 50 degrees C, pH 5 with a blend of cellulase and hemicellulase enzymes. Fermentation of both glucose and xylose was carried out using yeast. Co-fermentation was carried out at 32 degrees C. Ammonia was added to adjust the initial pH to 6. The incoming sugar monomers were converted to ethanol within 48 hours.