Results are reported of quantum density functional theory (DFT) calculations for methoxy radical adsorption on the (111) surfaces of copper, silver and gold. The metallic surfaces are modeled by clusters of seven atoms chosen to simulate the top, bridge, hcp hollow and fee hollow sites. A control test on the use of these small clusters was performed by running a calculation on a 22-atoms cluster. A comparison between the energetics of adsorption on the different sites identifies the fee hollow position as the preferred one for CH(3)O adsorption on the metal surfaces considered and the methoxy C-O axis is found to be perpendicular to the surface. It is shown how the methoxy radical binds on the hollow sites of copper, silver and gold metallic surfaces, the three oxygen p orbitals are found to interact strongly with the nearest neighbour metallic atoms except for the top position where only the p orbital aligned along the direction of the oxygen-metal atom is involved. In all cases, there is a charge transfer of approximately 0.6-0.8e from the metal atoms to the methoxy radical. The bonding of the methoxy radical on the surfaces studied has a largely ionic character. The calculated adsorption parameters and vibrational frequencies of the adsorbed species are in good agreement with the available experimental data. (C) 2000 Elsevier Science B.V. All rights reserved.