NOVELTY - Producing alcohols from biomass, comprises (a) pretreating the biomass in a pretreatment reactor (4) by steam explosion, (b) performing an enzymatic hydrolysis of a pre-treated substrate contained in the effluent in the presence of cellulolytic and/or hemicellulolytic enzymes, (c) performing an alcoholic fermentation of solubilized sugars contained in hydrolyzate to alcohols in the presence of alcohol-producing microorganism, (d) performing extraction of alcohols from fermented effluent, and (e) recycling, upstream of or in the reactor, aqueous internal flow.    USE - The method is useful for producing alcohols such as ethanol, propanol, isopropanol and butanol with carbon atoms from biomass (claimed) such as lignocellulosic biomass (such as hardwood and softwood) obtained from food industries and paper mills.    ADVANTAGE - The method ensures efficient and economical production of alcohols from biomass with high yield (99%) and without formation of degradation products.    DETAILED DESCRIPTION - Producing alcohols with two or more carbon atoms from biomass, comprises (a) pretreating the biomass in a pretreatment reactor (4) by steam explosion so as to provide an effluent containing a pre-treated substrate, (b) performing an enzymatic hydrolysis of the pre-treated substrate contained in the effluent in the presence of cellulolytic and/or hemicellulolytic enzymes so as to produce hydrolyzate containing the solubilized sugars, (c) performing an alcoholic fermentation of solubilized sugars contained in hydrolyzate to alcohols with two carbon atoms in the presence of alcohol-producing microorganism so as to produce a fermented effluent, (d) performing extraction of alcohols with two carbon atoms from the fermented effluent, and (e) recycling, upstream of or in the pre-treatment reactor, at least one aqueous internal flow comprising at least one alcohol with n carbon atoms, where n is 2-5, where the alcohol, when the n is 2 carbon atoms, is mixed with at least one other alcohol so as to retrieve the output of a vapor effluent containing alcohols in the pre-treatment reactor.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a process for producing alcohols.    Conduit (1)    Charge preparation unit (2)    Line (3)    Pretreating reactor (4)    Extraction/purification unit. (12)