The structure, vibration, and electronic structure of H-2 molecule adsorbed on (ZrO2)(n) (n = 1-6) clusters were investigated with density functional theory. We found that H-2 is easily absorbed on the top Zr atoms of (ZrO2)(n) (n = 1-6) clusters. The Zr5O10H2 cluster has the lowest binding energies in the ZrnO2nH2 (n = 1-6) clusters. By analyzing vibrational frequency and Mulliken charge, the H-O and Zr-H bonds were found to be formed in different sized ZrnO2nH2 clusters. The dissociation mechanism of H-2 shows that the charge transfers from (ZrO2)(n) cluster to H-2 due to the important role of the orbital hybridization between the cluster and H-2 molecule. With increasing the number of H-2 molecule adsorbed on (ZrO2)(n) clusters, the adsorption favors to the sites with low coordinate number, and these adsorption modes present a symmetrical tendency. Copyright (c) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.