Layered zinc hydroxychloride (Zn(5)(OH)(8)Cl(2)center dot H(2)O) synthesized by hydrolyzing the ZnO particles in aqueous ZnCl(2) solutions at 100 degrees C for 48 h was outgassed at different temperatures ranging from 100 to 250 degrees C for 2 h and the structure and adsorption properties of the products were examined by various means. Outgassing at 100-150 degrees C eliminated the H(2)O molecules in interlayer of zinc hydroxychloride. The layered structure of zinc hydroxychloride was disintegrated at 175 degrees C by breaking the OH center dot center dot center dot Cl hydrogen-bond in interlayer to form curled thin films composed of poorly crystallized beta-Zn(OH)Cl and ZnO, leading to the increment of the specific surface area from 4 to 39 m(2)/g. The beta-Zn(OH)Cl was decomposed at 225 degrees C to form ZnO. The crystallinity of ZnO was increased on elevating the outgassing temperature, giving rise to the UV absorption property. The H(2)O and CO(2) adsorption measurements revealed that the zinc hydroxychloride outgassed at 100-150 degrees C possessed a high H(2)O and CO(2) adsorption selectivity, and the selectivity diminished by the formation of thin films of ZnO above 175 degrees C. (C) 2009 Elsevier Ltd. All rights reserved.