The influence of poly(acrylic acid) (PAA) concentration and molecular weight on the filtration behavior of CeO2 slurries with 20 nm particle size was studied. Low-viscosity suspensions could be produced by adsorbing a monolayer of PAA that covered the nanoparticles. For all suspensions investigated, the cake permeability was lower than predicted by the Kozeny-Carman equation and decreased with increased filtration pressure because of the presence of a compressible PAA layer 3-5 nm thick on the surface of the particles. The permeability of the nanoparticulate cakes decreased with increased polymer addition because of clogging.