Fast pyrolysis of bagasse pretreated by sulfuric acid was conducted in a fixed bed reactor to prepare levoglucosenone (LGO), a very important anhydrosugar for organic synthesis. The liquid yield and LGO yield were studied at temperatures from 240 to 350 degrees C and sulfuric acid loadings from 0.92 to 7.10 wt.%. An optimal LGO yield of 7.58 wt.% was obtained at 270 degrees C with a sulfuric acid pretreatment concentration of 0.05 M (corresponding to 4.28 wt.% sulfuric acid loading). For comparison, microcrystalline cellulose pretreated by 0.05 M sulfuric acid solution was pyrolyzed at temperature from 270 degrees C to 320 degrees C, and bagasse loaded with 3-5 wt.% phosphoric acid was pyrolyzed at temperature from 270 degrees C to 350 degrees C. The highest yield of LGO from bagasse was 30% higher than that from microcrystalline cellulose, and treatment with sulfuric acid allowed a 21% higher yield than treatment with phosphoric acid. (C) 2011 Elsevier Ltd. All rights reserved.