Trithiolato-bridged arene osmium complexes of the general formula [(p-cymene)(2)Os-2(mu-SR)(3)](+) (R = C6H5, [1](+); C6H4-p-Me, [2](+); C6H4-p-OMe, [3](+); C6H4-p-Pr-i, [4](+); C6H4-p-But, [5](+); CH2C6H5, [6](+); CH2CH2C6H5, [7](+); CH2C6H4-p-Bu-t, [8](+)) were synthesized in ethanol by reacting the p-cymene osmium dimer [(p-cymene)(2)Os-2(mu-Cl)(2)Cl-2] with the corresponding thiol (RSH). The complexes were isolated as their chloride salts, and fully characterized by spectroscopic methods. The single-crystal X-ray structure analysis of the salt [6]Cl is also presented. These osmium complexes were found to be highly cytotoxic towards several cancerous cell lines (A2780, A549, B16F10, HeLa) with IC50 values comparable or even better to those found for doxorubicin. (C) 2014 Elsevier B.V. All rights reserved.