A process for reducing the viscosity of polysaccharides such as starch by treatment with hydrogen peroxide in the presence of an acylated polysaccharide as an activator is described. The acylated polysaccharide is used in particular in an amount which is equivalent to at least 1 acyl group per 100 monosaccharide units. The hydrogen peroxide is preferably used at 2-20 wt.%, with respect to the total of polysaccharide and acylated polysaccharide.
