Hydrotalcite-derived Mg,Al-mixed oxides (MO) with variable Mg/Al ratios (3, 1, 1/3) were impregnated with 17 wt.% of CeO2 and evaluated for SOx removal under conditions similar to those of FCC units. The catalyst with Mg/Al= I, for which both an Mg(Al)O periclase-type and an MgAl2O4-spinel were present before sulfation, showed the best performance for both SOx uptake and catalyst regeneration. The results from TPR/MS and XRD along reduction indicate the existence of different species in the sulfated samples. The reduction of these sulfate species leads to the evolution of SO2 or H2S, Mg(Al)O being the solid product in any case. Our results do not support the assertion that the reduction of S6+ to S2- is a consecutive reaction. The evolution of SO2 upon reduction decreases as the relative importance of the spinet-phase in the mixed oxides increases. The sulfates formed from the spinet-phase are more easily reduced than those from the periclase phase. The growth of the sulfate phase in the early stages of sulfation destroys the small mesopores of the mixed oxide. Upon regeneration, the sulfate phase is consumed and larger mesopores are formed. (c) 2005 Elsevier B.V. All rights reserved.