Improved fractionation process conditions for wood dissolution with switchable ionic liquids (SILs) were determined. The short time, high temperature (STHT) system was introduced as a selective and efficient way to extract components from lignocellulosic material. A SIL based on monoethanol amine (MEA) and 1,8-diazabicyclo-[ 5.4.0]-undec-7-ene (DBU) formed via coupling with SO2, was applied as a solvent in a 1: 3 weight ratio with water. In essence, selective dissolution of mainly lignin was achieved by means of the aqueous SIL at 160 degrees C (similar to 6.1 bar corresponding to the vapor pressure of water) in 2 h and in a pressure vessel, for both hard-and soft-wood. About 95 wt-% of wood lignin was extracted. The dissolved components in the spent SIL were recovered by the addition of an antisolvent whereupon over 70% of the dissolved components were recovered; the recovered fraction contained 19 wt-% hemicellulose while the rest of the material was in essence lignin. The non-dissolved, fluffy material contained similar to 70 wt-% cellulose and similar to 20 wt-% hemicellulose - a consistency resembling that of Kraft pulp.