Four nanocomposite catalysts namely MnFe2O4, MnFe2O4-SiC, MnFe2O4-TiO2 and MnFe2O4-diatomite, were synthesized and characterized by X-ray diffraction (XRD) and N-2 adsorption (BET specific surface area). Measurements of the catalysts' complex permittivity and permeability in the microwave (MW) frequency range of 0.5-18 GHz showed MnFe2O4-SiC composites to be the best MW absorbers. The surface temperature of MnFe2O4-SiC (1450 degrees C) under MW was higher compared to those of the other three catalysts, indicating that silicon carbide (SiC) was an effective support. MW-assisted experiments demonstrated that the degradation of RBR X-3B with MnFe2O4-SiC reached 92%, achieved 70% of TOC removal and exhibited lower toxicity with 5 min MW irradiation, proving MnFe2O4-SiC to be an excellent microwave catalyst. These findings are important regarding the development of efficient sorbents that are effective microwave absorbers as well as catalysts of rapid degradation of pollutants. (C) 2014 Elsevier B.V. All rights reserved.