Xylan extraction from corncobs was studied in lab-scale with NaOH solution enhanced by ultrasonication. The effects of NaOH concentration, temperature, corncobs to NaOH solution ratio, and sonication time on extraction performance were appraised in this study. Results showed that the xylan extraction should be operated at the following conditions, e.g., 1.8 M NaOH solution, corncobs to NaOH solution ratio of 1:25 (w/w), sonication at 200 W ultrasound power for 30 min at 5 min intervals, and 60 degrees C. In addition, the hydrolysis of xylan to xylose by xylanase under concentrated ultrafiltration with polyamide (PA) capillary fibres was investigated. During the operation of hydrolysis, the substrate (xylan) solution containing xylanase was circulated along the shell side and the product (xylose) was continuously extracted from shell side to lumen side. The whole process provided the basis for further study of economically producing xylose from corncobs. (c) 2005 Published by Elsevier Ltd.