Sonochemical and hydrothermal routes have been used in different conditions for preparation of CdCO3 and Cd(OH)(2) nanoparticles at air and inert atmospheres, respectively. The CdO nanoparticles were obtained by heating of CdCO3 and Cd(OH)(2) nanoparticles at 400 degrees C. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) microscopy have been used to characterize the nanoparticles. The XRD results of intermediate products showed that the origin of CdCO3 is CO2 from air atmosphere. (C) 2009 Elsevier B.V. All rights reserved.