The synthesis, DNA binding properties and cytotoxicity of a series of Ru(II)-arene complexes containing oligocationic ammonium-functionalized triarylphosphines, of the type Ru(p-cymene)Cl-2(L) (L - oligocationic phosphine), are reported. The complexes are highly charged (the overall charge states being +3 and +6) and circular dichroism spectroscopy and gel electrophoresis studies indicate that the compounds interact strongly with DNA via electrostatic interactions. Despite forming strong interactions with DNA, the complexes exhibit only modest cytotoxicities on the human ovarian cancer cell lines A2780 and A2780cisR. (C) 2010 Elsevier B.V. All rights reserved.