Treatment of the known half-sandwich complexes of the type [(η 6-C 6 H 6)RuCl 2 (P(OR) 3)] (R = Me or Ph) with SnCl 2 yielded three new half-sandwich ruthenium complexes (C1-C3): [(η 6-C 6 H 6)RuCl(SnCl 3)(P(OMe) 3)] (C1), [(η 6-C 6 H 6)RuCl(SnCl 3)(P(OPh) 3)] (C2) and the bis-stannyl complex [(η 6-C 6 H 6)Ru(SnCl 3) 2 (P(OMe) 3)] (C3) by facile insertion of SnCl 2 into the Ru-Cl bonds. Treatment of the known complexes [(η 6-C 6 H 6)RuCl(SnCl 3)(PPh 3)] and [(η 6-C 6 H 6)RuCl 2 (PPh 3)] with 4-dimethylaminopyridine (DAMP) and ammonium tetrafluoroborate afforded the complex salts: [(η 6-C 6 H 6)Ru(SnCl 3)(PPh 3)(DAMP)] + BF 4 − (C4) and [(η 6-C 6 H 6)RuCl(PPh 3)(DAMP)] + BF 4 − (C5) respectively. Complexes C1-C5 have been fully characterized by spectroscopic means (IR, UV-vis, multinuclear NMR, ESI-MS) and their thermal behaviour elucidated by thermal gravimetric analysis (TGA). Structural characterization by single crystal X-ray crystallography of the novel complex C2 and [(η 6-C 6 H 6)RuCl 2 (P(OPh) 3)], the latter having escaped elucidation by this method, is also reported. Finally, the cytotoxicity of the complexes was determined on the A2780 (human ovarian cancer), A2780cisR (human ovarian cis-platin-resistant cancer), and the HEK293 (human embryonic kidney) cell lines and discussed, and an attempt is made to elucidate the effect of the stannyl ligand on cytotoxicity.