The interaction Of SO2 With the inverted spinel MgFe2O4 in the presence and in the absence of oxygen has been studied by FT-IR spectroscopy in the temperature range 300-773 K. SO2 adsorbs in the form of sulfito complexes that transform to sulfato complexes both in the presence and in the absence of oxygen. Evidence is found for a catalytic effect of the ferric oxide component in the oxi dation Of SO2. Sulfate species are stable up to 773 K. Pyridine adsorption experiments show that sulfated magnesium ferrite is a Lewis acidic solid and does not present Bronsted acidity.