Abstract An LCAO-MO calculational procedure was used to determine the heat of chemisorption (Q) for an adatom monolayer on a transition metal film. Characteristic parameters of the metal such as Fermi energy (E F), bandwidth, and position of the d atomic level (ε d), parameters of the adatom such as energy level (ε A), and interaction parameters (β) between adatom and metal were varied to determine the dependence of Q on metal position in the periodic table. Adatoms with one valence orbital (for simplicity, of the s type) and with occupation of zero (acceptor), one (radical), or two (donor) were considered. On-top and hole sites each led to similar conclusions. In accordance with model results, Q depends monotonically on β (ε A − E F ) . As the d occupation increases within a given transition series, the Q value decreases for the radical and donor cases but increases for the acceptor. These curves are rather flat, in agreement with model results and experimental trends.