This work deals with soot oxidation under SO2 presence over CuO doped CeO2 prepared using two routes, coprecipitation (CP) and citrate acid complex-combustion synthesis (CA) TPO. XRD. BET, H-2-TPR, O-2-TPD, FIR and XIS are utilized to correlate the performance and physicochemical features of catalysts. The Jesuits show that solid solutions are formed due to Cu2+ cations entering into the ceria lattice This reorganization increases the amount of oxygen vacancies and then creates mote surface active species (Ce4+/Ce3+ and O+), and Increases the reducibility and oxygen storage capacity of catalysts. thus promoting catalytic activity for soot oxidation Both for Cu-0 05,Ce-0 95-CA and Cu0 05Ce0 95-CP after TPO in the presence of various concentrations of SO2, more Ce4+/Ce3+ redox couples, and more active oxygen species, detected by XPS technique and FIR, respond to the better activity When compared to Cu0 05Ce0 95-CP, the better reducibility and greater OSC, and active oxygen species of Cu0 05Ce0 95-CA coincide with its better activity A possible pathway of soot oxidation over Cu0 05Ce0 95-CA is proposed, based on the relationship of the performance and the physicochemical features of catalysts, which pathway follows the mechanism associated with redox couple and oxygen spill over effect. (C) 2010 Elsevier B V All rights reservecl