Ba1-xLaxTiO3/multi-walled carbon nanotube (MWCNT) nanocomposites with different concentrations of La3+ doping, were synthesized by a solvothermal process. The prepared nanocomposites had a hybrid microstructure in which Ba1-xLaxTiO3 nanocrystals with diameter of 10-30 nm were firmly immobilized on the MWCNTs sidewalls. Electromagnetic (EM) wave absorption properties of La-doped BaTiO3/MWCNT nanocomposites were investigated in the 7.5-18 GHz frequency range for an absorber thickness of 1 mm. The reflection loss (RL) calculated from the EM parameters of the samples, moved to low frequencies with increasing La3+ doping. The widest absorption bandwidth, with the lowest frequency range, was observed in a nanocomposite doped with 1.5 at% La3+. An RL exceeding -5 dB for this sample was obtained in the frequencies ranging from 9.6 to 16.3 GHz, with the optimal RL of -17.4 dB at 10.9 GHz, due to enhanced interfacial polarization resulting in developed epsilon ''(r). In addition, the RL for the sample shifted to the low frequency region and the peaks became sharper in the 2-18 GHz frequency range with increasing absorber thickness. For BaTiO3/MWCNT nanocomposites, La3+ doping can greatly improve the EM wave absorbing ability in a thin absorber thickness and the donor-doped nanocomposites show promise for application in EM wave shielding materials with broad absorption bandwidths. (C) 2011 Elsevier B.V. All rights reserved.