A polymer nanocomposite was produced by acrylonitrile-butadiene-styrene (ABS) and α-alumina (Al2O3) nanoparticles through melt compounding. The nanosized α-alumina was prepared through sol-gel process using aluminum nitrate and citric acid. The particle size was analyzed by X-ray diffraction and scanning electron microscopy (SEM) studies. The nanocomposites were characterized through tensile strength, Young's modulus, strain% at break, flexural strength, flexural modulus, and impact strength. The ABS/Al2O3 nanocomposites are found to have slightly higher Young's modulus, but lower tensile strength, strain% at break, flexural and impact strength than the virgin ABS. But its flexural modulus increases with increasing Al2O3 content in ABS matrix. The d-spacing was calculated in nanocomposites to evaluate the interaction between Al 2O3 and ABS. The particle distributions in nanocomposites were studied by SEM. The fractured surfaces of tensile test samples were also examined through SEM and show that the ductile fracture of ABS is converted to brittle fracture with addition of Al2O3. © 2008 Society of Plastics Engineers.