Abstract In an earlier paper results were reported for monolayer chemisorption of HCl, Cl 2 and F 2 onto the Si(001) surface. It has now been discovered that the Cl interactions were not treated correctly in these SLAB-MINDO molecular orbital calculations. The main purpose of this Letter is thus to present the corrected results for both HCl and Cl 2 chemisorption. Dangling bond configurations are now found to represent the lowest energy configurations for both chemisorption processes. This is in contrast to the previously published results in which a bridge site-topology was determined to be the minimum energy structure for Cl 2 chemisorption onto the Si(001)2 × 1 reconstructed surface. These new results are shown to be in good agreement with self-consistent ab-initio Hartree-Fock cluster calculations, with the first-principles local-density calculations of Kruger and Pollmann, and with experiment.