AbstractMaize hull hemicelluloses can be extracted almost quantitatively by simple water treatment (“prehydrolysis”) in a flow reactor at 165–180°C. Severe decomposition of pentosans is thus avoided. Concomitant solubilized starch can be separated from hemicelluloses by degradation with glucoamylase as was shown on an analytical scale. The obtained xylan (yields around 25%) is partly depolymerized and about 50% of original arabinose present in the side chains are split of. Nevertheless the isolated product, which is well soluble in water, is still highly branched and shows aDPwof 37