The interaction of alkali ions with the Cu(100) and Ag(100) surfaces is studied using the DFT method. The results of the B3LYP calculations performed for five cations, Li+, Na+, K+, Rb+ and Cs+, adsorbed on the surface of the M-12(6,6) cluster (M = Cu, Ag) are presented. On both metals the interaction is found to be strongest for the Li+ ion and weakest for the Cs+ ion. Three sites were tested for the adsorption of ions on the (100) surface: top, bridge and hollow. For the two smaller ions, Li+ and Na+, the below site is found to be the most stable. For the three larger ions the top position is more attractive. Nevertheless, the energy value at the different sites for a given ion in most cases, differs by less than 5 kJ mol(-1). For all ions the interaction with silver is stronger than the interaction with copper.