A process for the soil release treatment of surfaces of textile and nontextile materials, in which cationically modified hydrophilic nanoparticles based on crosslinked polymers of (a) 60 to 99.99% by weight of one or more carboxyl-containing ethylenically unsaturated monomers or salts thereof, (b) 0 to 40% by weight of one or more water-insoluble monoethylenically unsaturated monomers, (c) 0.01 to 30% by weight of one or more polyethylenically unsaturated monomers, (d) 0 to 25% by weight of one or more sulfonic acid- and/or phosphonic acid-containing monomers or salts thereof, (e) 0 to 30% by weight of one or more water-soluble nonionic monomers are applied to the surface of the materials from an aqueous dispersion, where the dispersion of the hydrophilic nanoparticles can be stabilized with anionic, nonionic and/or betainic emulsifiers and/or protective colloids, and where the hydrophilic nanoparticles have a particle size of from 10 nm to 2 .mu.m and have been cationically modified by coating their surface with one or more cationic polymers, one or more polyvalent metal ions and/or one or more cationic surfactants.