A recent report by Mills et al. [1] compares their theoretical work on adsorption of molecular oxygen on gold cluster anions to previous experimental work performed in our laboratory. They present binding energies that seem to be inconsistent with the experiment, and suggest that the conclusions arrived at from the experimental results may be incorrect. In this comment, we provide a quantitative basis for criticizing the experimental method, showing the nature and magnitude of the inconsistencies, and providing a partial reconciliation with the theoretical results. (C) 2003 Elsevier Science B.V. All rights reserved.