Novel room-temperature vulcanized silicone rubber (RTV)/organic montmorillonite (OMMT) composites have been prepared. Di(2-oxyethyl)-12 alkane-3 methyl-amine chloride and hydrogen silicone oil were used as intercalation agents to treat Na(1)-montmorillonite and form two kinds of OMMTs. The structure and properties of OMMT were characterized by Fourier transform infrared spectroscopy and X-ray diffraction (XRD). The intercalation mechanism of different types of intercalation agents was proposed. RTV/OMMT composites were prepared using these OMMTs. Properties such as viscosity, hardness, tensile strength, elongation at break, and thermal stability were researched and compared. A combination of swelling test, XRD and transmission electronic microscopy studies was used to characterize the structure and reinforcing mechanism of these OMMTs. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 1293-1301, 2012