NOVELTY - Lignocellulose (1) is converted into sugars (21) by contacting lignocellulose containing solid biomass with cooking liquid (2) comprising formic acid and organic acid at 90-180 degrees C and biomass to liquid volume ratio of 1:3 to 1:50, separating pretreated solid residue (6) from spent cooking liquid (8), washing solid residue with washing liquid (11) comprising formic acid and organic acid, separating washed solid residue (15) from spent washing liquid (14), utilizing spent washing liquid to form cooking liquid, evaporating free organic acids (17) from solid residue and hydrolyzing enzymatically.    USE - Method of converting lignocellulose into sugars used as feed for preparing ethanol (claimed) for gasoline, or biochemicals or biofuels including levulinic acid, lipids, hydrogen, methane or acetic acid.    ADVANTAGE - The method easily removes formic acid from cooked biomass without requiring water-washing step and formic acid separation from water for formic acid recovery.    DETAILED DESCRIPTION - Lignocellulose (1) is converted into sugars (21) by contacting lignocellulose containing solid biomass with cooking liquid (2) comprising (vol.%) formic acid ( greater than or equal to 40) and organic acid ( greater than or equal to 50) at 90-180 degrees C and biomass to liquid volume ratio of 1:3 to 1:50, separating pretreated solid residue (6) from spent cooking liquid (8), washing solid residue with washing liquid (11) comprising (vol.%) formic acid ( greater than or equal to 40) and organic acid ( greater than or equal to 50), separating washed solid residue (15) from spent washing liquid (14), utilizing spent washing liquid to form cooking liquid, evaporating free organic acids (17) from solid residue and hydrolyzing enzymatically.    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic diagram of lignocellulose conversion to sugars.    Lignocellulose (1)    Cooking liquid (2)    Pretreated solid residue (6)    Spent cooking liquid (8)    Washing liquid (11)    Spent washing liquid (14)    Washed solid residue (15)    Organic acids (17)    Evaporated washed solid residue (18)    Sugars (21)