A model calculation of the dephasing rate of an adsorbate vibration due to electron-hole pair scattering on a metal surface is presented. The standard Newns-Anderson model is used to describe the adsorbate-metal surface system in terms of a single electronic adsorbate level and a tight-binding metal band. The perturbation of the vibrational motion by the coupling between adsorbate and metal electrons is included to second order. The magnitude of the dephasing rate and its temperature dependence are obtained in terms of the model parameters and the adsorbate-orbital projected electronic density of states. It is in reasonable agreement with recent experimental data for CO on Ni(111). © 1987 The American Physical Society.