Silicon-based ceramics and aluminum nitride (Si/AlN) were fabricated by pyrolysis of polysilazane (PSZ) coated AlN at 1600 degrees C in air, Ar, N-2 and NH3 atmospheres. The results from XRD, XPS and SEM/EDS revealed the existence of crystalline phase of Si-based ceramics on AlN particles including SiO2 in Si/AlNair, Sic whisker in Si/AlNAr, SiC whisker/Si3N4 grain in Si/AlNN2, and Si3N4 ceramics in Si/AlNNH3. It was found that the thermal conductivity of silicone rubber filled with Si/AlN hybrid fillers which were fabricated in Ar and NH3, was improved. This might be due to the existence of nanoscale SiC whiskers and a thermal conductive layer of Si3N4 on Si/AlNAr and Si/AlNNH3 surface, respectively. Thus, it can be suggested that Si/AlN hybrid fillers, especially for the case of Si/AlN(Ar and NH3), can be applicable to use as thermally conductive fillers. This work may have found to be an alternative way to improve thermal conductivity, but more work needs to be done to really achieve significant improvement. (C) 2014 Elsevier B.V. All rights reserved.