La0.6Sr0.4MnO3/polyaniline nanocomposites were successfully synthesized via in-situ polymerization of aniline, with ammonium persulfate as oxidant and NaDBS as surfactant. The spectroscopic characterization indicated that the La0.6Sr0.4MnO3 nanoparticles were dispersed in the matrix of polyaniline. The polyaniline continuously deposited on the surface of La0.6Sr0.4MnO3 nanoparticles. Many patches of small cloud-like structures were formed in the nanocomposites. It was found that the dielectric loss of electric dipole polarization produced by PANI and the magnetic loss produced by LSMO can be combined in the composite to improve microwave absorption performance. In addition, the characteristics of microwave absorption properties of the nanocomposites can be adjusted by controlling the compositions of the nanocomposites. (C) 2013 Elsevier B.V. All rights reserved.