Process for oxidizing sulfur dioxide

In a process for removing sulfur dioxide from a gas stream containing the same prior to passing said gas stream to the ambient atmosphere by converting the sulfur dioxide in a low temperature, liquid phase, catalytic reaction to sulfuric acid, the improvement comprising contacting the sulfur dioxide containing gas stream and a gas containing oxygen with an acidic aqueous solution containing from 3 ppm to 8000 ppm of pentavalent vanadium ion and from 3 to 200 ppm of a divalent manganese ion at a temperature in the range of 0.degree. to 100.degree. C and continuing said contact until the concentration of sulfuric acid in said aqueous solution reaches up to 55% by weight.