Polycarbonate (PC)/cerium (IV) oxide (CeO 2) composites are prepared by a melt-compounding method using a twin-screw extruder. The effect of the CeO 2 content on the damping property of the composites was investigated using scanning electron microscopy, dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA). In addition, the composites' mechanical properties were studied through tensile and impact tests. The DMA results revealed that the addition of CeO 2 (0.5 wt%) improved the damping property of the composite. TGA showed that the thermal stability was improved when the CeO 2 became 1 wt%. Mechanical tests revealed that both the tensile and impact strengths were substantially improved when 1 wt% CeO 2 was added. Finally, it can be concluded that the 0.5 wt% CeO 2-filled PC composite can be used as a structural damping material.