(EN) This process for decomposing lignocellulose material by cooking it with an acidfied mixture of 70 to 30 parts by volume of water and 30 to 70 parts by volume of an organic solvent at a temperature from 160��C to 210��C, withdrawing the spent cooking liquor from the cellulose residue, if any, and distilling and then condensing organic solvent and volatile decomposition products from the withdrawn cooking liquor(s) to precipitate lignin, is characterized in that (A) the pH of the solvent mixture is maintained from 3.5 to 1.7 and (B) for the recovery of cellulose the organic solvent is ethanol and the acid is oxalic acid, or (C) for the saccharification of the lignocellulose the organic solvent is acetone and the acid is a strong mineral acid, namely hydrochloric, sulfuric, nitric or phosphoric acid or the strong mineral acid together with a neutral salt thereof. If total saccharification is desired the process is preferably performed in two steps using (a) water/acetone/mineral acid at pH 3...