MnO nanoparticles (MnONP) decorated SiC whiskers (SiCw) with superior electromagnetic (EM) wave absorption performances were successfully synthesized by combining a hydrothermal and thermal annealing process. The microstructural feature and the content of MnONP of these MnONP/SiCw composites could be effectively controlled by the hydrothermal temperature, resulting in the adjustable EM wave absorption capacity. Compared with the poor EM wave absorption property of pristine SiCw (-10.48 dB), the MnONP/SiCw heterostructures achieve substantially enhanced microwave absorption performances, attributing to the suitable impedance matching and improved loss ability arose from the synergetic effect between MnO and SiC, whose minimum reflection loss (RLmin) is improved to -15.84 dB for MnONP/SiCw obtained at 80 degrees C (S-80), to -15.17 dB for MnONP/SiCw obtained at 100 degrees C (S-100), and to -55.10 dB for MnONP/SiCw obtained at 120 degrees C (S-120), respectively. The MnONP/SiCw composite not only exhibits enhanced microwave absorption property, but also presents wider effective absorption bandwidth (EAB), reaching up to 5.4 GHz for S-80, 3.6 GHz for S-100 and 5.2 GHz for S-120 in comparison with pristine SiC (1.5 GHz). This work is expected to provide an effective approach to enhance EM wave absorption property of dielectric materials by incorporation of MnO and the MnONP/SiCw composites could be as a promising candidate for EM wave absorption applications. (C) 2019 Elsevier Inc. All rights reserved.