The adsorption dynamics of O₂ on Al(1 1 1) has been studied exptl. using mol. beams and laser spectroscopy as well as theor. using a multi-dimensional multi-electronic surfaces model. Expts. find that: (i) abstractive chemisorption is operative at all translational energies; (ii) it increases markedly with translational energy; and (iii) rotational excitation of the mols. suppresses the abstraction process. The model calcns. semi-quant. reproduce the exptl. findings and demonstrate that: (i) a nonadiabatic description is necessary to reproduce the exptl. results and that (ii) the rotational hindrance is due to a restricted cone of acceptance in direction of the surface normal.