The adsorption of water molecule on a Cu(1 1 1) surface at 25 K was studied by infrared reflection absorption spectroscopy (IRAS). The four characteristic absorption bands in a v(OD) stretching region were observed on Cu(1 1 1) surface and assigned to be OD stretchings from dimer and hexamer water cluster molecules. The appearances of the key OD stretching bands observed on M(1 1 1) (M = Cu, Ni, Pt) and Ru(0 0 1) surfaces indicate that water dimer and hexamer clusters are coadsorbed dominantly on those surfaces at 25 K. (c) 2005 Elsevier B.V. All rights reserved.