Process for the preparation of an additive-containing anionic clay comprising the steps of (a) milling a physical mixture of a divalent metal compound and a trivalent metal compound, (b) calcining the physical mixture at a temperature in the range 200-800° C., and (c) rehydrating the calcined mixture in aqueous suspension, wherein an additive is present in the physical mixture and/or the aqueous suspension of step (c). With this process additive-containing anionic clays with a homogeneous additive distribution can be prepared.