Chemisorption of SO2 from smelting plant exhaust gases in a single sieve plate column was investigated. Main parameters were SO2 and O-2 gas and H2SO4, FeSO4 and Al-2(SO4)(3) liquid concentrations on reaction rate and equilibrium in FeII-EDTA solutions. Absence of inhibitors with this kind of flue gases promote fast kinetics. Optimal process conditions with 3% wt. FeSO4 catalyst up to 2000 ppm SO2. Maximum yield of 16% H2SO4 could be achieved considering optimal liquid/vapor ratio, oxygen surplus and insert salt concentrations.