Culms of bamboo grass (Sasa senanensis Rehd.) were treated with saturated steam at 197 degrees C for 10 min in the presence of various acid catalysts in order re, improve enzymatic susceptibility. Catalyst levels were varied at 5, 10, 20 and 30 mmol kg(-1) original material. The catalysts were Lewis acids, NH4Cl, (NH4)(2)SO4, acetic acid and organic acid anhydrides. The extent of enzymatic hydrolysis of steamed substrate was improved by the addition of catalyst. The acid catalysts strongly modified the steam treatment of bamboo grass culms. Overall recovery of the steamed solids decreased with increase in concentration of the catalyst. Conversion yields from 60 to 70%, based on polysaccharides present in the original material, were achieved by catalyzed steaming followed by enzymatic hydrolysis.