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Mixed oxides were synthesized by co-precipitation of a Cu source in combination with Al, Fe or Mn corresponding salts as precursors. The materials were calcined at 600 and 1000 °C in order to crystallize the phases and to mimic the reaction conditions of the catalytic application. At 600 °C a mixed spinel structure was only formed for the combination of Cu and Mn, while at 1000 °C all the materials showed mixed spinel formation. The catalysts were applied in three-way catalysis using a reactor with a gas mixture containing CO, NO and O₂. All the materials calcined at 600 °C displayed the remarkable ability to oxidize CO with O₂ but also to reduce NO with CO, while the pure oxides such as CuO and MnO₂ were not able to. The high catalytic activity at 600 °C was attributed to small supported CuO particles present and imperfections in the spinel structure. Calcination at 1000 °C crystallized the structure further which led to a dramatic loss in catalytic activity, although CuAl₂O₄ and CuFe₂O₄ still converted some NO. The materials were characterized by X-ray diffraction (XRD), Raman spectroscopy, H₂-Temperatrue Programmed Reduction (H₂-TPR), N₂-sorption and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX).