NN-Di(2-hydroxyethyl)-N-dodecyl-N-methyl ammonium chloride was used as an intercalation agent to treat Na+-montmorillonite and form a novel type of organic montmorillonite (OMMT). An OMMT master batch (OMMT-MB) was prepared by solution intercalation and was used in the preparation of high-temperature-vulcanized silicone rubber (HTV-SR)/OMMT-MB nanocomposites. The properties, such as the tensile and thermal stability, were researched and compared with those of composites directly incorporated with OMMT or aerosilica. A combination of Fourier transform infrared spectroscopy, wide-angle X-ray diffraction, and transmission electron microscopy studies showed that HTV-SR/OMMT-MB composites were on the nanometer scale, and their structure was somewhat hindered by the presence of OMMT. The results showed that the tensile properties of HTV-SR/OMMT-MB and HTV-SR/OMMT systems were better than those of pure HTV-SR. Compared with those of HTV-SR/OMMT-20%, the tensile strength and elongation at break of HTV-SR/OMMT-MB-20% were improved about 1.5 and 0.9 times, respectively. This was probably due to the nanoeffect of the exfoliated silicate layers. Moreover, the tensile strength of HTV-SR/OMMT-MB-20% was nearly equal to that of HTV-SR/aerosilica-20%, and the elongation at break even showed much improvement. Additionally, the thermal degradation center temperature of the HTV-SR/OMMT-MB-20% nanocomposite was increased by 30 degrees C compared with that of the HTV-SR/OMMT-20% composite. (c) 2007 Wiley Periodicals, Inc.