The adsorption dynamics of O-2 on Al(111) has been studied experimentally using molecular beams and laser spectroscopy as well as theoretically using a multi-dimensional multi-electronic surfaces model. Experiments find that: (i) abstractive chemisorption is operative at all translational energies; (ii) it increases markedly with translational energy; and (iii) rotational excitation of the molecules suppresses the abstraction process. The model calculations semi-quantitatively reproduce the experimental findings and demonstrate that: (i) a nonadiabatic description is necessary to reproduce the experimental results and that (ii) the rotational hindrance is due to a restricted cone of acceptance in direction of the surface normal. (C) 2003 Elsevier Science B.V. All rights reserved.