NOVELTY - Biomass feedstock utilization involves treating comminuted biomass with hydrogen peroxide (1-8 wt.%) and an organic solution of formic acid and acetic acid at 125-155 degrees C in a solid-liquid mass ratio of 1:5-1:10 for 20-50 minutes to obtain a mixed slurry. The concentration of total organic solution utilized is 70-95 wt.%, where acetic acid and formic acid are in the ratio of 1:1-1:12. The obtain slurry is treated with hydrogen peroxide, formic acid, and acetic acid at a controlled temperature of 20-100 degrees C, where ratio of solid to liquid material is 1:4-1:20 to obtain a mixture.    USE - Method for utilizing biomass feedstock (claimed).    ADVANTAGE - The method enables to utilize biomass feedstock in convenient manner with improved extraction time.    DETAILED DESCRIPTION - Biomass feedstock utilization involves treating comminuted biomass with hydrogen peroxide (1-8 wt.%) and an organic solution of formic acid and acetic acid at 125-155 degrees C in a solid-liquid mass ratio of 1:5-1:10 for 20-50 minutes to obtain a mixed slurry. The concentration of total organic solution utilized is 70-95 wt.%, where acetic acid and formic acid are in the ratio of 1:1-1:12. The obtain slurry is treated with hydrogen peroxide, formic acid, and acetic acid at a controlled temperature of 20-100 degrees C, where ratio of solid to liquid material is 1:4-1:20 to obtain a mixture. Hydrogen peroxide utilized is 4-8wt.% and the total acid concentration utilized is 60-70 wt.%. The total acid concentration utilized is in the molar ratio of 1:3:12-1:1:12. The obtained mixture undergoes solid-liquid separation and then treated with water at 25-90 degrees C to obtain resulting slurry with pulp consistency of 3-7 wt.%. The resulting slurry is filtered to separate cellulose content at 60-110 degrees C at 101-301 kilopascal to obtain resultant product. The solid content in the resultant product is 70-95 wt.%. The resultant product undergoes washing to obtain filtered product. The obtained filtered product is stirred with dilute acid and undergoes liquid bleaching to obtain xylose and desired lignin.