Abstract: Lignocellulosic biomass (11) is processed to produce organic chemicals by (a) subjecting the biomass to a first hydrolysis (14) to hydrolyse hemicellulose, to form a liquid component comprising the products of hemicellulose hydrolysis in solution, and a solid component comprising cellulose and lignin; (b) then subjecting the solid component to a second hydrolysis (20), so as to hydrolyse cellulose and vaporise the resulting products of cellulose hydrolysis; and (c) then condensing (22) the resulting vapours to form an aqueous solution (25) containing the products of cellulose hydrolysis. After the first hydrolysis (14) and before the second hydrolysis (20), the process also comprises subjecting the solid component to a washing step (16). In this washing step (16) the solid component is washed with the aqueous solution (25) that contains the products of cellulose hydrolysis. Hence the resultant solution contains the products of both the first and the second hydrolysis steps (14, 20).