Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The microstructural, morphological, optical and water-adsorption properties of nanocrystalline ZnO thin films and ZnO nanowires were studied and compared. The ZnO thin films were obtained by a sol-gel process, while the ZnO nanowires were electrochemically grown onto a ZnO sol-gel spin-coated seed layer. Thin films and nanowire samples were deposited onto crystalline quartz substrates covered by an Au electrode, able to be used in a quartz crystal microbalance. X-ray diffraction measurements reveal in both cases a typical diffraction pattern of ZnO wurtzite structure. Scanning electron microscopic images of nanowire samples show the presence of nanowires with hexagonal sections, with diameters ranging from 30 to 90 nm. Optical characterization reveals a bandgap energy of 3.29 eV for the nanowires and 3.35 eV for the thin films. A quartz crystal microbalance placed in a vacuum chamber was used to quantify the amount and kinetics of water adsorption onto the samples. Nanowire samples, which have higher surface areas than the thin films, adsorb significantly more water. (C) 2012 Elsevier B.V. All rights reserved.2135964Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CLAFSwedish Government Strategic Research Area Grant in Materials ScienceCITEDEFCONICETPEDECIBA-FisicaANII (Agencia Nacional de Investigacion e Innovacion)Universidad de la Republica, in Montevideo, UruguayConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq [490580/2008-4]