The catalytic activity of different samples of catalysts known in the field literature and obtained by us in the laboratory, through the decomposition of hydrogen peroxide at the laboratory installation, was studied. The catalytic activity of following catalysts Centaur, Quantum DM1-65, AC-Mn1, AC-Cu1, AC-Co1, AC-Mn2, AC-Mn1+KMnO4, AC-Mn2+KMnO4 was evaluated at different mixer speeds and different particle size of the catalyst. It was found that the sample AC-Mn1 + KMnO4 (22.86ml O2 /5min) has the highest catalytic activity, followed by Centaur (7.7ml O2 /5min) and AC-Co1 (6.8ml O2 /5min). The other samples have a lower catalytic activity. Grinding the Centaur catalyst to dust resulted in altered catalytic activity. The speed of mixing is also of great importance, which can lead to the destruction of the catalyst and to the reduction of its catalytic activity. The fastest kinetic process of decomposition of hydrogen peroxide occurs on the AC-Mn1 + KMnO4 sample. Next steps will include the study of the evaluation of the centers responsible for the catalytic activity of the samples AC-Mn1 + KMnO4, AC-Co1- catalysts obtained in the laboratory of Ecological Chemistry. The Centaur catalyst is well known in field literature, as one of the best catalysts, which oxidizes hydrogen sulphide from deep waters and has a wide application in making these categories of water potable. The best catalysts will be tested for removing of pollutants, which exceed the maximum admissible limit in the deep waters of the Republic of Moldova.