Models of dithiolate rhenium(V)–oxo and –thio complexes and ReVII (ReVIIO2 and ReVIIOS) intermediates are studied computationally using DFT(B3LYP). The analysis of the Re–E bond (E = O, S) shows that the two lone pairs (Px, Py) on the oxo and thio ligands are strongly polarized to the ReV and ReVII centers, forming partial π bonds, which agree with the bond‐order analysis of 2 (one σ + two partial π bonds). The lone pairs on the thio ligands are less polarized than on the oxo ligand. The ReVO and ReVS bond strengths are calculated to be approximately 163.7 ± 1.8 kcal mol–1 and 123 ± 3 kcal mol–1, respectively. The ReVIIO and ReVIIS bond strengths are calculated to be 118.7 ± 1.2 kcal mol–1 and 80.5 ± 3.5 kcal mol–1, respectively. The calculated oxo– and thio–rhenium bond strengths and the thermochemistry of the OAT (oxygen‐atom transfer) cycle support that ReVIIO2 and ReVIIOS are the key intermediates in the OAT (oxygen atom transfer) and SAT (sulfur atom transfer) reactions.