This invention aims to develop a process for fractionation of lignocellulosic biomass by contacting lignocellulosic biomass with treatment liquid in close system at temperature not over 200° C. and pressure of 5 to 20 bars, wherein said treatment liquid comprises water-miscible part that comprising formic acid, alcohol, and water and water-immiscible part that comprising alkyl acetate. The lignocellulosic biomass may be selected from rice straw, bagasse, corncobs, corn stem, palm waste, grass, pineapple shell, bamboo, or mixture thereof.
