As the starting materials of organic light-emitting diode (OLED) getter, calcium carbonate (CaCO3) particles with various shapes and crystal structures have been successfully prepared with additives (L64 or PEGPG), which contain blocks of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO). These CaCO3 particles were calcinated into highly crystalline calcium oxide (CaO) nanoparticles with high capacity of water adsorption up to 14.23 wt.%. The CaCO3 and CaO particles prepared at various conditions were characterized using the field emission scanning electron microscopy (FE-SEM), Fourier transform infrared microscopy (FTAR), X-ray powder diffraction (XRD), and dynamic vapor sorption (DVS) method. (C) 2008 Elsevier Ltd. All rights reserved.