We report infrared reflection-absorption and thermal desorption spectra of CO adsorbed at low temperature (30 K) on the surface of MgO(0 0 1) thin films. The high similarity of the observed IR bands as compared to data reported for MgO(1 0 0) single crystals and sintered MgO particles gives evidence for the identical surface morphology of the different substrates. CO adsorption series taken at constant temperature/ variable pressure, variable temperature/constant pressure, as well as isotope mixing experiments reveal almost no diffusion of CO on MgO(0 0 1) at low temperature, but high adsorbate mobility at slightly elevated temperature. (c) 2006 Elsevier B.V. All rights reserved.