Ordered mesoporous carbon (OMC) coated with thorny-like Fe-Ni alloy composites have been successfully synthesized. The electromagnetic (EM) parameters of Fe-Ni alloy/OMC/paraffin wax composites were measured. Interestingly, the mu '' values of Fe-Ni(0.2)/OMC were very negative from similar to 7 to 18GHz and the minimum value was -0.7, which are mainly caused by the eddy current. The reflection loss (RL) values were calculated with the measured EM parameters based on the transmission line theory. Results showed that the effective absorption bandwidth (<-10 dB) of Fe-Ni(0.2)/OMC/paraffin wax composites with the thickness of 2.00 mmcould reach up to 4.8 GHz. The enhanced EM wave-absorbing properties of the composites could be attributed to well impedance matching between the absorber and air. Moreover, the enhanced dielectric loss and magnetic loss induced by Fe-Ni alloy also played a crucial role in the EM wave-absorbing process. (C) 2015 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.