A novel rubber-nanocomposite has been synthesized through the emulsion polymerization of styrene-butadiene rubber and nano antimony oxide using accelerators and antioxidant. Sulphur was used as vulcanizing agent. The synthesized SBR-nano antimony oxide was characterized by elemental analysis, FTIR, scanning electron microscopy, transmission electron microscopy and mechanical testing. On basis of the FTIR, the structure of the SBR-nano antimony oxide was proposed. The physico-chemical parameters have been evaluated for the SBR-nano antimony oxide. The aggregation nature of the synthesized rubber-nano composite was established by scanning electron microscopy (SEM). The effects of nano particles in polymer matrices have been evaluated for the SBR-nano antimony from TEM analysis. Mechanical behavior of the composites are found to improve consistently as nano- antimony oxide content in the composites increases owing to increased rubber- filler interaction. Tensile strength studies are found to be useful to assess the improvement of the mechanical properties of matrix.