Cadmium Oxide (CdO) hollow spheres have been synthesized by using carbon microsphere as sacrificial template. The products were characterized by X-ray powder diffraction (XRD), scanning electronic microscopy (SEM) and transmission electron microscopy (TEM). The average diameter and shell thickness of as-prepared hollow spheres are about 600 nm and 50 nm, respectively. The formation of hollow spheres was investigated and it was found that the shell formed when the heating temperature reached about 673 K and the sequential heat treatment could remove the carbon template. Moreover, the influence of other experimental parameters including concentration (0.1–5 M) and type of cadmium salts (cadmium chloride, cadmium acetate and cadmium nitrate, etc.) as well as type of solvents (water, ethanol and dimethylfomamide) were also investigated.