This paper reports a pilot-plant production process for xylo-oligosaccharides (mainly xylobiose and xylotriose) from corncob meal by steaming treatment followed by enzymatic hydrolysis and nanofiltration. The effects of corncob meal pretreatment, steaming temperature and time were investigated in order to obtain maximum extraction of xylan and to minimize the autohydrolysis of xylan into xylose. The enzymatic reaction was carried out using Aspergillus niger AN-1.15 endo-xylanase at 55degreesC and the optimum enzymatic hydrolysis time was 5 h. The conventional downstream processing for purification of xylo-oligosaccharides was incorporated with nanofiltration technology, giving benefits of energy saving and removal of monosaccharides. The final product from 40 kg of corncob meal was 10 dm(3) of xylo-oligosaccharide syrup (800 g dm(-3) total sugar), containing 74.5% xylobiose and xylotriose. (C) 2004 Society of Chemical Industry.