Enormous growth of automobile industry has encouraged the material developers to develop a wide range of property rich and cost effective filled composites. cenospheres (cs) are hard, rigid, light weight, waterproof, hollow spheres made largely of silica and alumina and filled with air or inert gas, produced as a byproduct of coal combustion at thermal power plants. in present study, composites were developed with acrylonitrile butadiene styrene (abs) and varied filler concentration of cenosphere (100-200 µm) from 0, 10, 15, 20, 25, and 30 wt% using co-rotating twin screw extruder and injection molded test specimens were prepared to study the effect of concentration of cs on the properties of cs filled abs composites. the cs was treated with 2 wt% silane coupling agent (kbm-503). the comparison of properties of composites filled with treated and untreated cs revealed that the composites with treated cs showed better mechanical properties due to the increased interfacial adhesion and same was confirmed by the sem micrographs. the increase in cs concentration improves dielectric strength and increases the specific gravity. the composites were also characterized by dsc, tga and dma.