Process for the production of ethanol and solvents from lignocellulosic biomass with recycle of a butyl wine obtained by fermentation of pentoses

The present invention discloses a method of producing alcohols and / or solvents from cellulosic or lignocellulosic biomass comprising at least a) a thermo-chemical pretreatment stage of a cellulosic or lignocellulosic substrate b) optionally a step of washing the pretreated substrate, and setting the pH c) enzymatic hydrolysis step the pretreated substrate, d) ethyl fermentation step hexoses and obtaining an ethyl wine; e) an extraction step f) a fermentation step butyl pentoses contained in at least one of the flows obtained in the previous steps and obtaining a butyl wine; wherein at least a portion of butyl wine is recycled upstream of at least one of steps of enzymatic hydrolysis and / or ethanol fermentation.