A process for the regeneration of sulfuric acid contaminated with hydrocarbons and water to produce pure concentration acid comprising: contacting sulfuric acid contaminated with hydrocarbons and water with oxygen and elemental sulfur in the presence of a vanadium containing catalyst in a reaction zone, maintaining at least a portion of the acid in the liquid phase, converting hydrocarbon to carbon oxides and water, and converting sulfur and sulfurdioxide to sulfurtrioxide, separating the reactor effluent into a vapor stream and a liquid stream and cooling and partially condensing of the vapor stream to concentrate clean acid.