The influence of the surface projected electronic structure on resonant charge transfer is investigated on the Cu(111) and Cu(100) surfaces using core hole clock spectroscopy and wave packet propagation computations. The charge transfer time of core excited Ar (2p(3/2)(5) 4s(1)) adsorbed in a dense Ar monolayer is 5.6 +/- 0.1 fs and 3.5 +/-10.1 fs for the Cu(111) and Cu(100) surfaces. A two times longer residence time on Cu(111) than on Cu(100) is also obtained from theory and is attributed to the differences in the projected electronic band structure of the two metal surfaces, especially to the different energies of the surface projected band gap. (c) 2006 Elsevier B.V. All rights reserved.