Reactions of the dinuclear ruthenium complex [(p-cymene)Ru(mu-Cl)3RuCl(C2H4)(PCy3)] with phenylacetylene or tert-butylacetylene gave the vinylidene complexes [(p-cymene)Ru(mu-Cl)3RuCl(=C=CHR)(PCy3)] (R = tBu, Ph), which were characterized crystallographically. With acetylene, however, a tetranuclear -carbide complex was obtained as evidenced by single-crystal X-ray analysis as well as by solid-state NMR spectroscopy. Experiments with fully 13C-labelled acetylene showed that acetylene was the carbon source for the carbide ligand.