Conditions for the preparation of etherified hemicelluloses from sugarcane bagasse with 2, 3-epoxypropyltrimethylammonium chloride (ETA) using sodium hydroxide as a catalyst in aqueous solution were studied comparatively. The extent of the etherification was measured by yield percentage and degree of substitution. The effects of reaction time of 3-7 h, reaction temperature of 50-80 degrees C, temperature of alkaline activation of 30-60 degrees C, and time of alkaline activation of 0-60 min on the reaction yield and degree of substitution were investigated in detail. The overall yield and degree of substitution were varied from 35.2 to 41.9% and from 0.14 to 0.33, respectively, by changing the reaction temperature and duration as well as time and temperature of alkaline activation. The new materials were characterized by FT-IR and 13C NMR spectroscopy, thermal analysis as well as GPC. It was found that the thermal stability of the hemicellulosic ethers decreased after chemical modification, and the molecular weights of the etherified hemicelluloses were lower than those of the native hemicelluloses. C-13 NMR spectra gave the evidence for etherification reaction and the quaternization of hemicelluloses occurred mainly at C-3 position. (c) 2007 Wiley Periodicals, Inc.