At present time, people are facing large varieties of environmental problems. One of them is the presence of sulfuric acid (H2SO4). One of the possible pathways of H2SO4 formation is via the oxidation of H2SO3. The latter is assumed to originate from abundant SO2 hydrating. Recently, a mechanism of H2SO3 formation on the ice surface in application to low temperatures has been described. Also, the rise of H2O2 concentration in polar core ice during last decades has been observed. To the best of our knowledge, the detailed molecular mechanism of H2SO4 formation from H2SO3 has been poorly investigated. Thereby, we suggest possibility of oxidation of H2SO3 by H2O2 on the ice surface. Here, ab initio gas phase calculations have been done with aim to understand the mechanism of H2SO4 formation by oxidation of H2SO3 with H2O2. Three different reaction pathways have been found.