Engineered nanoparticles are widely incorporated into a large number of consumer products due to their specific physico-chemical properties in comparison to bulk materials. Cerium dioxide nanoparticles (CeO2) are currently used in several applications: as a component of catalytic converters, as a UV blocking or polishing agent or as a diesel fuel additive. The fate of engineered nanoparticles in the aquatic environment is highly dependent on their aggregation, transport and surface chemistry. Interaction with natural organic matter (NOM) and solution chemistry are expected to play an important role in the behavior of nanoparticles in natural water. In our work we investigated the fate of cerium dioxide nanoparticles (JRC NM-212) in various models of natural waters. In particular, we adjusted the composition of some solutions according to the characteristic of the Geneva lake water. The influence of pH, ionic strength and concentration of NOM was also investigated by considering the CeO2 nanoparticle stability. Dynamic light scattering and electrophoretic measurement were used to study the surface charge and z-average hydrodynamic diameter of nanoparticles. Size distribution and visualization of nanoparticles were done by nanoparticle tracking analysis and scanning electron microscopy. We demonstrated the different aggregation behavior of CeO2 nanoparticles in varied aquatic conditions. Our results suggest that nanoparticles can enter the environment in their initial size and concentration of NOM plays an important role in modification of particle surface charge. The solution chemistry, i.e. presence of mono and divalent ions, as well as change of NOM concentration, lead to the aggregation, disaggregation or dispersion of nanoparticles in natural water.