The aim of this thesis is to develop novel modified VOx/Ce1-xMxO2 catalysts (M = Zr, Ti, Mn) that are capable of converting NOx and NH3 to N2 well below 300 °C at a high GHSV. Various methods of preparation of the supports, as well as the influence of the co-components (Zr4+, Ti4+, Mnn+), were investigated and evaluated to study the structural properties and catalytic activity. Furthermore, analysis of the catalysts under reaction conditions using in situ techniques, such as EPR, UV-Vis-DRS, and DRIFTS-spectroscopy, allowed the identification of structure-reactivity relationships.