The invention relates to a process for producing a hydrogel, which is performed in a reactor which has a body A which rotates about an axis of rotation and a metering system. A component comprising at least i) a soluble salt of an acidic or amphoteric oxygen-containing molecular anion and ii) a component comprising a precipitant are applied with the aid of the metering system to the surface of the rotating body A, such that a mixture of components i) and ii) flows over the surface of the rotating body A to an outer region of the surface of the rotating body A, the mixture leaves the surface and the pH of the mixture after leaving the surface of the body A is between 2 and 12. Additionally disclosed is the use of the resulting hydrogels for production of aerogels.