Bis(3-triethoxysilylpropyl) tetrasulfane (TSS) was reacted with the silanol groups of the commercially available clay, Closite((R))25A (C25A) to prepare TSS-C25A, which was melt-compounded with acrylonitrile-butadiene-styrene copolymer (ABS). The tetra sulfide groups of TSSC25A may chemically react with the vinyl groups of ABS to enhance the interaction between the clay and ABS. The ABS/clay composites exhibited much higher tensile strength and elongation at break than the neat ABS. Especially the elongation at break of ABS/TSS-C25A composite was 5 times higher than that of neat ABS. The X-ray diffraction patterns of the clay showed that the d(001), basal spacing was enlarged from 1.89 nm to 2.71-2.86 nm as a result of the compounding with ABS. According to the thermogravimetric analysis, the thermal decomposition of the composite took place at a slightly higher temperature than that of neat ABS. Intercalated/exfoliated coexisting structures were observed by transmission electron microscopy for the ABS/clay composites. (R) 2007 Wiley Periodicals, Inc.