Abstract This study aims to assess the role of iron plaque (IP) on cerium (Ce) uptake and translocation by rice after CeO 2 nanoparticles (NPs) exposure over a 4 days period. A hydroponic experiment was performed under two IP levels (low and high) combined with two CeO 2 NPs size (14 nm and 25 nm). It was found that CeO 2 NPs as the main form was absorbed by rice due to limited NPs dissolution in hydroponic solution. IP significantly reduced surface-Ce, root-Ce and shoot-Ce accumulation, irrespective of CeO 2 NPs sizes. The reduced uptake of Ce was more obvious in NP 25 than NP 14. Ce accumulations decreased with increasing IP amounts. In IP treatments, the interactive attraction between NPs and root surface was weakened through the enhancement of hydrodynamic diameters and the reduction of ζ-potential of CeO 2 NPs in solution, as well as the reduction of |ζ| values of rice root, which reduced the Ce bioaccumulation in rice. PCA indicated the negative correlation between surface-Ce (IP-C-Ce and IP-A-Ce) and NPs size, and between shoot-Ce/root-Ce and IP-Fe/tissue-Fe. IP also decreased Ce translocation from root to shoot. A full life study indicated the reduction effect of IP on surface-Ce, root-Ce, shoot-Ce and grain-Ce accumulations. These findings are significant as they imply that the IP formation is a promising approach for preventing Ce accumulation in rice, which would regulate Ce uptake by rice in the following growth stages and decrease the health risk of CeO 2 NPs exposure in agricultural environment. Graphical abstract Unlabelled Image Highlights • IP significantly reduced Ce accumulation in rice under CeO 2 NPs exposure. • Ce accumulation in rice decreased with increasing IP amounts. • IP formation weakened the interactive attraction of NPs and root surface. [ABSTRACT FROM AUTHOR]