Reactions of size-selected copper cluster cations, Cu-n(+) (n = 3-7) and CunOm+ (n = 3-5; m = 1 and 2), with nitrous oxide molecules, N2O, have been investigated by use of a tandem mass spectrometer. N2O molecules adsorb sequentially on the odd-sized Cu-n+ to produce Cu-n(+) (N2O)(l), while the even-sized clusters give the reaction products, such as Cun-1O+(N2O)(l), involving both the oxidation and the N2O adsorption. Preadsorption of oxygen atoms promotes the sequential N2O-adsorption significantly, and in particular, Cu3O+(N2O)(3), Cu4O2+(N2O)(3), and Cu5O2+(N2O)(4) are produced dominantly from Cu3O+, Cu4O2+, and Cu5O2+, which shows the saturation of the adsorption with N2O. (C) 2012 Elsevier B. V. All rights reserved.