NOVELTY - Conversion (M1) of lignocellulosic biomass to sugars involves incubating lignocellulosic biomass having ligin, cellulose, and hemicellulose in ionic liquid (L1) to remove a portion of the lignin; replacing ionic liquid (L1) from the biomass by washing ionic liquid (L1)-incubated biomass with a liquid non-solvent for cellulose that is miscible with ionic liquid (L1) and water; contacting the washed biomass in aqueous buffered melieu having enzymes capable of hydrolyzing cellulose and hemicellulose, and converting portion of polysaccharides to hexose and pentose sugars.    USE - In a conversion of lignocellulosic biomass to sugars (selected from hexose and pentose sugars) useful for producing fuels, chemicals, polymers and other materials (claimed).    ADVANTAGE - The method improves the efficiency (in terms of yield and reaction rates) of saccharification of lignocellulosic biomass; has a major impact on the overall economics of sugar production from biomass; is able to handle large biomass to ionic liquid (L1) ratios during incubation; is able to accomplish saccharification at very low enzyme loadings; is able to perform well with large biomass particles; provides potential for total recovery and multiple reuse of the ionic liquid (L1) employed to pretreat the biomass; is able to produce a hydrolysate free of compounds that can inhibit the downstream processing of the constituent sugars and allows for recovering most of the lignin in biomass following saccharification.    DETAILED DESCRIPTION - Conversion of lignocellulosic biomass to sugars involves providing any lignocellulosic biomass containing ligin, cellulose, and hemicellulose; incubating the biomass in an ionic liquid (L1) for a time at a temperature to remove or redistribute a substantial portion of the lignin such that the ionic liquid (L1) is able to penetrate the hemicellulose and the crystalline cellulose buried in the hemicellulose and swell these structures significantly; replacing all or most of the ionic liquid (L1) from the biomass by washing the ionic liquid (L1)-incubated biomass with a liquid non-solvent for cellulose that is miscible with the ionic liquid (L1) and water; contacting the washed biomass in an aqueous buffered melieu containing enzymes capable of hydrolyzing both cellulose and hemicellulose and converting a portion of these polysaccharides to hexose and pentose sugars. An INDEPENDENT CLAIM is included for disruption (M2) of the structure of lignocellulosic biomass and swelling of the cellulose and hemicellulose portions involving incubating the biomass in the ionic liquid (L1) for a time at a temperature to remove or redistribute a portion of the lignin such that the ionic liquid (L1) is able to penetrate the hemicellulose and the crystalline cellulose buried in the hemicellulose and swell these structures significantly; replacing all or most of the ionic liquid (L1) from the biomass by washing the ionic liquid (L1)-incubated biomass with a liquid non-solvent for cellulose that is miscible with the ionic liquid (L1) and water; processing the above washed biomass with chemical and biochemical reagents to affect the conversion of the swollen biomass to useful chemicals efficiently.