A simple and rapid microwave-assisted combustion method was developed to synthesize CdO nanospheres (CNS). The study suggested that the application of microwave heating to produce the homogenous CNS was achieved in a few minutes. The structure and morphology of the as-prepared CNS were investigated by means of X-ray diffraction (XRD), Fourier transforms infrared spectra (FT-IR), high resolution scanning electron microscopy (HR-SEM), Energy Dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), diffused reflectance spectroscopy (DRS) and Photoluminescence (PL) spectroscopy. The XRD confirmed the formation of face centered cubic structure of CdO. The formation of CdO phase is also confirmed by FT-IR. The formation of spherical hollow nanospheres was confirmed by HR-SEM and TEM and their possible formation mechanisms were also tentatively proposed. The optical properties were determined by DRS and PL spectra. © 2011 Elsevier B.V.