Degradation of cereal beta-glucan is usually attributed to enzymes or acid hydrolysis. However, there is evidence that polysaccharides are also susceptible to OH-radical induced depolymerisation, and that these radicals can be produced in cereal food systems. The role of Fenton type oxidation was demonstrated in pure beta-glucan solution (0.6%). An addition of ascorbic acid (10 mM) or its oxidation product, dehydroascorbic acid, in the presence of iron sulphate resulted in a significant decrease of the solution viscosity and molecular degradation of beta-glucan. The viscosity decrease was inhibited by introducing a OH-scavenger (glucose) in the solution or limiting oxygen level in the sample solution. This demonstrates the role of OH-radicals in beta-glucan scission and suggests oxidative cleavage to be a potential threat for the stability of beta-glucan in certain fibre enriched products.