CO2 adsorbed on Pt(111) is a system that has several attractive features that make it suitable for studies of the role of internal degrees of freedom on the sticking process. In particular, this relatively long and linear molecule has a low energy vibrational mode. We have carried out measurements of the nondissociative sticking coefficient, S0, of CO2 on the Pt(111) surface in the zero coverage limit as a function of incident kinetic energy, Ei, at different angles of incidence. A most interesting feature of the measured S0 for this physisorption system is its slow decline from 0.6 at Ei=60 meV towards a value of S0≊0.1 at the highest measured energy of 1.2 eV. Our classical trajectory studies suggest that the observed high energy tail of S0 is primarily due to translational–rotational (T–R) energy transfer in the initial collision of the molecule with the surface while the effects of the intramolecular vibrations on S0 are negligible. The calculated S0 depends nonmonotonically on the rotational anisotropy of the molecule–surface interaction. This is shown to be an effect of the dramatic influence of the number of bounces made by the two ends of the molecule against the surface in the initial collision on the T–R energy transfer.