During the period of January 16 through 21, 2011 Dr Daniela Šojić, assist. prof., and Sanja Kler, junior researcher, stayed at the Institute of Material Sciences and Engineering, University of Szeged and worked on the joint research in the frame of the IPA project. The aim of the experiments was to monitor and compare the degradation of the pharmaceutical preparation metoprolol and herbicide thiamethoxam under UV light (254 nm), O3 and UV/O3 (by LC-DAD and spectrophotometry). The degradation under the given conditions was carried out in the waters of different origin (distilled, thermal and Danube water). Samples were also prepared for ionic chromatographic measurements to monitor release of chloride, sulfate, nitrate, and ammonium ions. Besides, samples were prepared for TOC measurements to monitor the degree of mineralization of the parent compound and intermediates formed during the degradation.