Process for the preparation of an additive comprising TiO2 particles dispersed on a support of pseudo-layered phyllosilicate-type, comprising the dispersion in water of the support, the acid activation of the support and the high-shear dispersion of the support with the TiO2 particles Use of the particles obtained by this process as additives with photocatalytic activity for water purification and disinfection, for purification of polluted gas streams and to provide materials, in particular construction materials, with self-cleaning, biocide, deodorization and/or pollution reduction properties in the presence of air and ultraviolet light.