In this paper, we present a study on the preparation of ceria nanopowder by Supercritical Antisolvent technique and its use as catalysts support for water gas shift reaction. The effect of the concentration of ceria precursor and the solution flow rate was evaluated on particle size and granulometric distribution. The increase of concentration led to an increase in the average particle size, whereas the solution flow rate had a negligible effect. The platinum/ceria catalyst was prepared by wet impregnation and fully characterized; SEM and TEM-EDX showed a mean particle size of around 50 nm and a good dispersion of the active component. The results of the activity tests highlighted a good performance of the SAS-derived catalyst, that showed higher CO conversion with respect to a catalyst obtained from commercial ceria nanopowder. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.