This paper studies the role of the catalytic support on microwave-assisted catalytic wet peroxide oxidation (MW-CWPO) with Fe as active phase. Experiments were carried out with and without MW using catalysts of Fe on activated carbon (Fe/AC) and gamma alumina (Fe/gamma-Al2O3). Phenol (100 mg.L-1) was used as target pollutant, operating at pH 3, 120 degrees C, 100 mg.L-1 catalyst concentration and the theoretical stoichiometric amount of H2O2 (500 mg.L-1). MW radiation promotes hot spot formation on the surface of AC, enhancing HOX center dot generation, so that the rate of mineralization is significantly increased with respect to non-assisted CWPO. Under these conditions, phenol oxidation proceeded essentially through direct aromatic ring breakdown, yielding carboxylic acids, while the formation of the highly toxic intermediates hydroquinone and p-benzoquinone were barely detected. The Fe/AC catalyst showed a better performance than the Fe/gamma-Al2O3 one, which can be explained by the much higher MW absorption on AC, which, in fact, showed to be a good MW-CWPO catalyst by itself. Meanwhile, the results proved that Fe/gamma-Al2O3 was basically transparent to MW, and deposition of condensation byproducts on the surface hindered the activity of the Fe/gamma Al2O3 catalyst. (C) 2017 Elsevier B.V. All rights reserved.