In this work, we investigate the thermal conductivity of a three-component composite consisting of FeCr metal core aluminum oxide shell particles with a highly mesoporous shell layer. This composite showed highly enhanced thermal conductivity compared to typical two-component composites consisting of uni-modal particles. The improved thermal conductivity was found to be the result of excellent thermal contact conductance through the shell layer between the core particle surface and the continuous polymer medium. There was no effect from the enhancement of the thermal conductivity in the shell layer itself because the predicted thermal conductivity of the shell layer is significantly reduced by phonon scattering at the boundaries of the nanocrystals of,a size less than a phonon mean free path in the alumina in the shell layer containing a columnar-like pore morphology. The thermal conductivity of the three-component composites containing core shell particles with a nanostructured shell layer was well predicted from the modified core shell percolation theory, which considered the effects of phonon scattering and pores. (C) 2014 Elsevier Ltd. All rights reserved.