Mathematical modeling of a new sulfur dioxide oxidation method in sulfuric acid production has been carried out. The method is based on the use of the nonstationary state of the catalyst surface, in particular, the absorption properties of active component of vanadia catalysts in relation to SO,. The idea of the process is that the catalyst bed undergoes periodic cycling of the feed between air flow and a reaction gas mixture, containing SO,. The directions of air and gas mixture flow are opposite. The unsteady-state kinetic model of SO, oxidation over vanadium catalyst is used to describe dynamics of the catalyst state. The influence of different parameters on SO, conversion and overall process performance is investigated. According to the modeling results, this method provides a decrease of the SO, outlet content in the waste gases down to 50 ppm and thereby avoids the need for tail gas cleanup. The process may be easily applied to the second stage of a conventional DC/DA (double contact/double absorption) sulfuric acid plants.