Process for the manufacture of oxidized starch by reacting an aqueous slurry of starch with a peroxide compound, the reaction being carried out in the presence of ozone or by irradiating the slurry with UV light, the amount of peroxide compound used being lower than 30 % by weight calculated on the basis of the weight of dry starch. The oxidized starch can be used as additive for the paper industry or for the food industry.