Ag-(b)(2+) species were detected by electron paramagnetic resonance (EPR) on silver loaded over ceria by impregnation in a previous work. Contrasting the EPR simulation with the experimental measurements evidenced that, upon propene oxidation, the Ag-(b)(2+) species transform into two clusters each containing 2 Ag-(b)(2+) and 1 Ag+ species. This cluster is composed of two parallel electron spins (dimer) and three nuclear spins (trimer). Such a result led us to suggest that initially, Ag-(b)(2+) species clusters were formed by three parallel electron spins. The ferromagnetic character of Ag-(b)(2+) species may explain their catalytic performance towards total oxidation of propylene. (C) 2018 Elsevier B.V. All rights reserved.