The objectives of this study were to statistically study the effects of reaction conditions of temperature, acid concentration, and reaction time on manure components of cellulose, hemicellulose, lignin, and nitrogen during dilute acid treatment of dairy manure; and to further optimize the accumulation of cellulose for later enzymatic conversion to glucose. A 2(3) full factorial design was adopted to investigate the effects of the reaction conditions on each individual component and later followed by a 3-factor central composite design which was used to obtain the optimal conditions for cellulose accumulation. The results indicated that acid was the most important factor for changes of all the components. The results also showed that two other individual factors, reaction time and temperature, as well as the interactions among all three factors had significant influences on the changes. In addition, the optimal conditions for cellulose accumulation were 2.8 h reaction time, 140 degrees C reaction temperature, and 1.0% acid concentration. Under these conditions cellulose content reached 31.0% while hemicellulose, lignin and nitrogen content were 3.2%, 20.8% and 2.4%, respectively. (c) 2006 Elsevier Ltd. All rights reserved.