The surface coverage of a series of rhenia-alumina catalysts prepared by equilibrium adsorption was determined by low-temperature CO adsorption. The results show a linear increase in the coverage of the Re oxide on the alumina support up to 24% with increasing Re loading from 0 to ca. 5.6 wt%. This is consistent with a uniform build-up of the surface species. The coverage values measured by this method agreed very well with those obtained by ion scattering spectroscopy.