Abstract The catalytic decomposition of nitrogen dioxide (NO 2 ) was investigated over 18 metal oxides (Al 2 O 3 , SiO 2 , ZrO 2 , SnO 2 , TiO 2 , V 2 O 5 , Cr 2 O 3 , MnO 2 , Fe 2 O 3 , Co 3 O 4 , NiO, CuO, ZnO, MgO, CaO, La 2 O 3 , CeO 2 , and Nd 2 O 3 ). The relationship between the specific rates of the decomposition of NO 2 and the enthalpy changes ( − ΔH ) for the formation of metal oxides (Me x O y ) (Me x O y−1 +1/20 2 → Me x O y shows a V- shaped curve with a minimum at − ΔH around 700 kJ/mol. This suggests that the mechanism dealt with in this article switches at − ΔH =700 kJ/mol.