A central composite factorial design was used to examine the influence of independent variables of the ethanol pulping of wheat straw (viz. processing temperature and time, and ethanol concentration) on the yield and Shopper-Riegler index of the resulting pulp, and on various physical properties of paper sheets (viz. breaking length, stretch, burst index, tear index and brightness) obtained from it. By using the BMDP software suite, equations that relate each dependent variable to the different independent variables were obtained, and these reproduce the experimental results for yield, Shopper-Riegler index and brightness with errors less than 10%, and all other properties of the paper sheets to within 25%, over the temperature (140-180 degreesC), time (60-120 min) and ethanol concentration (40-80%) ranges allowing the production of pulps spanning a broad range of yields (from 37-79%). Ensuring the optimal breaking length (3550 m), stretch (1.42%), burst index (1.62 kN/g) and tear index (4.77 mNm(2)/g) entails using high temperature and medium-to-low ethanol concentration and time values; these conditions decrease the yield and brightness below their optimum levels (78.91 and 30.50%, respectively). However, high temperature, in combination with low ethanol concentration and short time, can be used to save solvent in the operations of recovery and recycling and to increase production. The values thus obtained for the dependent variables differ by less than 22% from their predicted optimum levels in the worst case. (C) 2002 Elsevier Science Ltd. All rights reserved.