NOVELTY - Production of soluble sugars involves preparing enzyme solution, adding biomass to the enzyme solution, repeatedly adding remaining biomass to obtain solid loading of 10-30% in the final reaction mixture, reacting final reaction mixture for 5-120 minutes to obtain biomass hydrolyzate, separating solid-liquid contents of the biomass hydrolyzate to obtain filtrate comprising soluble sugars and enzyme, and residue of unhydrolyzed biomass and adsorbed enzyme, separating the soluble enzyme, and recycling residue and separated soluble enzyme.    USE - Production of soluble sugars such as polysaccharides and monosaccharides, preferably glucose (claimed) used for producing fuels and chemicals including ethanol, and food/pharma applications.    ADVANTAGE - The method enables economical production of soluble sugars having highest final glucose concentration of 50-150 g/L, with high yield and reaction rate in reduced period of time, and minimizes sugar loss. Enzymes are efficiently recovered and recycled.    DETAILED DESCRIPTION - Production of soluble sugars involves preparing enzyme solution having pH of 4-6 in reactor vessel at 40-60 degrees C, adding biomass with holocellulose content of 70-100% and moisture content of 10-80 weight/weight% to the enzyme solution, while maintaining pH and temperature to obtain initial reaction mixture containing predetermined biomass and enzyme, in ratio 1:104-1:106 (Kg of biomass/FPU of enzyme), repeatedly adding remaining biomass for 30-90 minutes to obtain solid loading of 10-30% in the final reaction mixture, reacting final reaction mixture for 5-120 minutes to obtain biomass hydrolyzate, separating solid-liquid contents of the biomass hydrolyzate to obtain filtrate comprising soluble sugars and enzyme, and residue of unhydrolyzed biomass and adsorbed enzyme, separating the soluble enzyme from soluble sugars present in the filtrate, and recycling residue and separated soluble enzyme to maintain the predetermined ratio of biomass and enzyme. The biomass and enzyme ratio is maintained in the range of 1:103-1:105 (Kg of biomass/FPU of enzyme). During reaction of final mixture, 40-80% solubilization of biomass is achieved.    DESCRIPTION OF DRAWING(S) - The drawing shows a flowchart of gradual feed addition of biomass.