NOVELTY - The device comprises a digestion container for receiving biomass bales, a feed opening (1) for the biomass bales, and a discharge opening (2) for removing the treated biomass from the digestion container. A stationary or movable injection device (4) for preheating acid/water mixture is arranged in the digestion container. The preheated acid/water mixture is provided, via a filling pipe and a supply pipe (14), in an interior of the digestion container. A hydrolyzate resulting from a hydrolytic decomposition is discharged from the digestion container by a hydrolyzate outlet.    USE - The device is useful for a hydrothermal decomposition of dried, ligneous lignocellulosic-containing biomass in the form of bales.    ADVANTAGE - The device allows rapid, effective and economical hydrothermal decomposition of dried, ligneous lignocellulosic-containing biomass with less consumption of power.    DETAILED DESCRIPTION - The device comprises a digestion container for receiving biomass bales, a feed opening (1) for the biomass bales, and a discharge opening (2) for removing the treated biomass from the digestion container. A stationary or movable injection device (4) for preheating acid/water mixture is arranged in the digestion container. The preheated acid/water mixture is provided, via a filling pipe and a supply pipe (14), in an interior of the digestion container. A hydrolyzate resulting from a hydrolytic decomposition is discharged from the digestion container by a hydrolyzate outlet. A filter- and guide element for separating liquid hydrolyzate from the solid biomass is arranged in a bottom area of the digestion container. The injection device is formed as an insertion probe and is introduced via a guide cylinder (3) from a top of the digestion container in the biomass bales for injecting the acid/water mixture into the bales. The device further comprises a unit for monitoring a temperature and a pH, a pressure control unit, a safety valve (10) and/or a vapor outlet. An INDEPENDENT CLAIM is included for a method for a hydrothermal decomposition of dried, ligneous lignocellulosic-containing biomass in form of bales.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a device for a hydrothermal decomposition of dried, ligneous lignocellulosic-containing biomass (Drawing includes non-English language text).    Discharge opening (2)    Guide cylinder (3)    Injection device (4)    Safety valve (10)    Supply pipe. (14)