The present invention relates to a method for producing oligosaccharides from a lignocellulose biomass, including at least the following steps: a) pretreating the biomass in a pretreatment reactor such as to supply an effluent containing a pretreated substrate; b) carrying out, in a reactor, an enzymatic hydrolysis of the pretreated substrate contained in the effluent from step a) in the presence of cellulases, such as to produce a hydrolysate containing glucose, cellulases and water; c) sampling at least a portion, including a liquid fraction, of the hydrolysate from step b); d) reducing the water content of said portion of the hydrolysate sampled in step c) such that the liquid fraction of the hydrolysate has a water content of less than 65 % in water weight with respect to the total weight of the liquid fraction of the hydrolysate; and e) incubating, at a temperature between 40 and 70 DEG C, the hydrolysate from step d) for the time necessary to produce an oligosaccharide-rich effluent.