Dinuclear metal complexes have emerged as a promising class of unusually biologically active compounds. Acylpyrazolonato-bridged arene ruthenium complexes of the general formula [(arene)2Ru2(L′)Cl2] were synthesized in methanol by reacting the arene ruthenium dimer [(arene)RuCl2]2 with the corresponding acylpyrazolone ligands. The complexes were isolated and fully characterized by spectroscopic methods; the single-crystal X-ray structure analysis of [(cymene)2Ru2(L1)Cl2] is also presented. These ruthenium complexes were found to be cytotoxic towards epithelial cancerous cell lines to a comparable extent to cisplatin but with higher capacity to discriminate between normal and cancer cells.