Testing the activity of ceramic monolithic catalysts for the catalytic oxidation of BTEX compounds The aim of this work was to examine the effectiveness of different monolithic catalysts for the catalytic oxidation of a mixture of aromatic volatile organic BTEX compounds. BTEX compounds include benzene, toluene, ethylbenzene and xylene. BTEX compounds belong to volatile organic compounds (VOCs) that easily reach the environment and have a harmful effect on human health due to their toxic and carcinogenic properties. Catalytic oxidation is one of the available and frequently used methods for reducing the concentration of volatile organic compounds. The carriers on which the catalytically active components were applied were made using additive manufacturing techniques, i.e. molten filament production techniques and stereolithography (3D printed carriers). For comparison, commercial cordierite supports made using the extrusion technique were also used. Mixed metal oxides of manganese and iron (MnFeOx), manganese and zinc (MnZnOx), manganese and copper (MnCuOx), manganese and chromium (MnCrOx), manganese and cobalt (MnCoOx) and manganese and zinc (MnZnOx) were used as catalytically active components. Catalytic oxidation was carried out in a monolithic reactor under conditions of atmospheric pressure, in a wide temperature range and with a constant volume flow of reactants and air (92 cm^3 min^-1). The T10, T50 and T90 values (°C) corresponding to the temperatures for achieving 10%, 50% and 90% conversion of BTEX compounds were used as a criterion for comparing the effectiveness of monolithic catalysts. Based on the comparison of the T10, T50 and T90 values (°C) of cordierite supports with the same geometric surfaces (29 cm^2) with different catalytically active components applied, it was observed that the most effective catalyst is the cordierite support with applied MnFeOx as a catalytic layer. By comparing T10, T50 and T90 values (°C) for 3D printed monolithic supports with a deposited MnFeOx catalytic layer, it is concluded that the highest efficiency was achieved with the ZDP-FFF support, while the lowest temperature value was required to achieve 90% benzene conversion.