Oxidative decomposition of dilute nitrobenzene in air was carried out in a catalytic plasma reactor with an inner electrode made of sintered metal fibres (SMF) that also acted as catalyst. The parameters of the concentration, specific input energy, and gas residence time were optimized. The modification of the SMF inner electrode with transition metal oxides like MnOx and CoOx oxides promoted complete oxidation, especially at low input energy. CoOx/SMF showed higher activity than MnOx/SMF and SMF, and could oxidise completely 100 ppm of nitrobenzene at 300 J/L.