<p>A new series of tricarbonyl complexes of rhenium(I) in the “2 + 1” system with the bidentate ligand <i>N</i>,6-dimethylpyridine-2-carbothioamide ((CH<sub>3</sub>)NC<sub>5</sub>H<sub>4</sub>-CS-NH-CH<sub>3</sub>, MeLH<i>(Me)</i><sub>NS</sub>) and a monodentate ligand (halides Cl, Br, or I, and the pseudohalide NCS anion) was synthesized. The use of mixed ligands led to the formation of neutral tricarbonylrhenium(I) complexes [Re(CO)<sub>3</sub>(MeLH<i>(Me)</i><sub>NS</sub>)X] (X = Cl, Br, I, NCS) (<b>1</b>–<b>4</b>). Single-crystal X-ray diffraction was used to determine the crystal structures of all four compounds and those results were compared with molecular structures obtained from DFT calculations using the PBE0/def2-TZVPD approach. The complexes were also characterized by spectroscopic (FT-IR, NMR, and UV–vis) and analytical (HPLC, TGA, EA, ESI-MS) techniques. IR and UV–vis spectra were also calculated by DFT and TD-DFT methods. The cytotoxicity of these complexes was estimated using human ovarian cancer cell lines (A2780 and A2780cis), cervical cancer cells (HeLa), and non-cancerous human embryonic kidney cells (Hek-293). The toxicity of most complexes was moderate or low toward cancer cell lines (IC<sub>50</sub> = 46–231 μM) and similar against non-cancerous cells (IC<sub>50</sub> = 41-121 μM). Only the complex with chlorido ligand remarkably inhibited growth of ovarian cancer cells (IC<sub>50</sub> = 3 and 12 μM for A2780 and A2780cis, respectively). The cytotoxicity of <b>1</b> was higher than that of cisplatin.</p
