Titanium catalysts are important materials for many types of oxidation reactions. Conventionally prepared microporous titanosilicate, namely TS-1, is well-known catalyst used in oxidation reaction with hydrogen peroxide. Since the size restriction of pores in microporous catalysts limits their wide application, large effort has been invested in order to prepare new types of catalysts with expanded surface area and pore size. Such new type of catalyst, mesoporous TS-1, was compared with conventional microporous TS-1 in our study. Besides the typical reactions, e.g. epoxidations, oxidation of sulfides represents another important branch of application. This type of reaction leads to the preparation of organic sulfoxides and sulfones, which are important chemical intermediates and building blocks of pharmaceutical and agrochemical compounds. Our study is focused on the testing of both types of catalysts, i.e., microporous TS-1 and mesoporous TS-1, in the oxidation of methyl phenyl sulfide with 30% hydrogen peroxide, and the influence of the structure in conversions of reagents and the selectivity to products was described. Samples were studied using BET analysis and X-ray powder diffraction analysis. The morphology of the samples was observed by atomic force microscopy.Keywords: TS-1, titanosilicate, oxidation, atomic force microscopy, catalysis