TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Process: Stage (b) is performed using nitric acid as the nitrate ion source at a temperature of 60-80degreesC. Stage (c) is performed using 1-6, preferably 1-1.5% HNO3 at a temperature of 75-100degreesC for 30-180 minutes using alum as the aluminum compound. The nitrated biomass is washed between stages (c) and (d). Stage (d) is performed at pH 11-12 and a temperature of 80-100degreesC for 30-60 minutes. The extraction liquor from stage (e) is treated with an acid, preferably nitric acid, at pH 5-6 to precipitate lignin which is separated from the soluble hemicellulose. The cellulose recovered from stage (e) is washed, converted to glucose sugars and fermented to produce ethanol.Preferred Biomass: The biomass comprises:(A) Woody, grassy or straw material;(B) Corn stover, hemp or kenaf;(C) Shredded brush or hardwood; or(D) Shredded coniferous wood.Preferred Conditions: The nitric acid concentration in stage (c) for biomass (B), (C) and (D) is 2-2.5, 3-4, and 5-6% respectively. The cellulose extracted at stage (e) comprises at least 90, preferably at least 93% alpha-cellulose. EXAMPLE - 500g of rice straw was chopped into 2 inch lengths, washed to eliminate dirt etc. and shredded whilst sprayed with 200ml of 0.20% HNO3. This straw was digested at 80-95degreesC in 5l of a solution of 1.5% HNO3 and 0.15% Al2(SO4)318H2O for 30 minutes at atmospheric pressure. The nitrating solution was drained from the digester and the pressed straw was washed twice with 1l of water at 80degreesC. The nitrated and washed straw was submerged in 5l of water and NH4OH was added to pH 11.5 and alkaline extraction was performed at 100degreesC for 30 minutes. The liquor (containing lignin and hemicellulose) was separated from the cellulose. The cellulose was washed with 2l of water at 80degreesC. The cellulosic fraction had an O.D. yield of 40.4% and was 90% holo cellulose, 88% of which was alpha-cellulose. The black liquor drained from the cellulose was acidified to pH 6 with HNO3 to precipitate the lignin which was separated and concentrated by centrifugation. The residual liquor contained 6% hemicellulose sugars.