TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Component: The alkyl- or aryl sulfonic acids have 9-15C. The organic acid is soluble in water and can be extracted with organic solvent insoluble in water. The alkyl- or aryl-sulfonic acids are dodecyl-sulfonic acid, p-toluene-sulfonic acid, 1-naphthalene-sulfonic acid, 2-naphthalene-sulfonic acid, and/or 1,5-naphthalene-disulfonic acid. The organic acid is p-toluene-sulfonic acid, 2-naphthalene-sulfonic acid, and/or 1,5-naphthalene-disulfonic acid. The halogenated carboxylic acids are those having not greater than 20C such as trifluoroacetic acid, dichloroacetic acid, trichloroacetic acid, and/or perfluoro-octanoic acid. The organic acid is present in the aqueous solution at 0.1-5, preferably 0.5-2 wt.%. The organic solvent insoluble in water is halogenated hydrocarbons such as methylene chloride, monochlorobenzene, and/or dichlorobenzene; aromatic hydrocarbons such as toluene and/or xylene. The organic solvent insoluble in water is methylene chloride or toluene.    TECHNOLOGY FOCUS - POLYMERS - Preferred Method: The biomass is subjected to a preliminary grinding process before being put in contact with the aqueous solution of organic acid(s). The process comprises obtaining a first solid phase and a first aqueous phase. The first aqueous phase is subjected to extraction with an organic solvent insoluble in water. The organic solvent insoluble in water is evaporated, obtaining a second solid phase, comprising organic acid, and a second aqueous phase comprising sugar having 5-6C. The method comprises re-using the organic acid. The second aqueous phase comprising sugar having 5-6C, is directly used in fermentation processes for the production of alcohols. The first solid phase is directly used in an enzymatic hydrolysis process, for hydrolyzing cellulose to glucose. From the enzymatic hydrolysis of the first solid phase, a third solid phase comprising lignin and a third aqueous phase comprising glucose which derives from the hydrolysis of cellulose, are obtained. The third aqueous phase is directly used as raw material in fermentation processes for the production of alcohols. Preferred Component: The polysaccharide is cellulose and/or hemicellulose. The biomass is lignocellulosic biomass including products of cultures cultivated for energy use (for e.g. miscanthus, millet or common cane), including by-products, residues and wastes of the cultures or of their processing; products of agricultural cultivations, forestation and silviculture, comprising wood, plants, residues and by-products of agricultural, of forestation and of silviculture processing; agri-foodstuffs by-products intended for human feeding or zootechnics; residues, not subjected to chemical treatment, from paper industry; waste products coming from the separated collection of solid urban waste (e.g. urban waste of a vegetable origin or paper). The biomass is present in the reaction mixture at 5-40, preferably 20-35 wt.%. The first solid phase comprises lignin and cellulose. The first aqueous phase comprises sugar having 5-6C and the organic acid. The sugar is xylose. Preferred Condition: The method is carried out at 100-125 degrees C. The biomass is put in contact with the aqueous solution for 20 minutes-6 hours, preferably 30 minutes-3 hours. Preferred Dimension: The biomass is ground until particles having a diameter of 0.1-10, preferably less than 1 mm are obtained. EXAMPLE - Destructured biomass (5 g dry weight and containing 3.3 g dry weight cellulose), were suspended in acetate buffer (100 ml) at pH 5. An aqueous solution of the Celluclast (RTM: enzyme) (1.5 L) corresponding to 33 Filter Paper Units (FPU) and Novozym 188 (RTM: enzyme) corresponding to 409 beta -Glucanase Units (BGU) was subsequently added. The suspension thus obtained was kept under stirring, at 45 degrees C, for 72 hours. At the end of the reaction, insoluble residue (1.7 g dry weight) was separated, by filtration, comprising lignin (yield of 97% calculated with respect to the quantity of lignin present in the starting biomass). The remaining aqueous solution contained glucose (yield of 94% calculated with respect to the quantity of glucose present in the starting biomass).