The structures of CunOm+/0 and CunOmHl+/0 clusters are obtained by DFT calculations. Clusters with even and odd number of copper atoms can be, respectively represented as (Cu2O)(n)(+) and [(Cu2O)(n)Cu](+). The latter are highly symmetrical and show positive charge uniformly distributed on the Cu atoms, whereas in the former, one of the Cu2O subunits exhibits a higher positive charge. It is found that the divalent oxygen of Cu2O is the reactive site involved in cluster growing. The structures of CunOmH2+/0 and Cu2nOnH+/0, correspond, respectively to hydrated and hydrogenated clusters. (C) 2008 Elsevier B.V. All rights reserved.