An exhaust gas after-treatment system for an internal combustion engine, with a particle filter arranged downstream of an internal combustion engine for filtering soot out of the exhaust gas, and with an oxidation catalytic converter arranged upstream of the particle filter and downstream of the internal combustion engine for the oxidation of SO2 into SO3. The SO3 and/or precipitated H2SO4 serves for the oxidation of soot in the particle filter and thus for the regeneration of the particle filter.