The preparation of an electroactive material based on a (Ru(terpy)(CO)) frame (terpy = 2,2':6',2-terpyridine) has been achieved by the two electron reduction of trans- or cis-[Ru(terpy)(CO)Cl-2] complexes. During this electrochemical process, two chloride ligands are released and metal-metal bonds are formed. The highly coloured resulting compound containing Ru-Ru bonds can either be coated as a film on an electrode surface in acetonitrile electrolyte or generated as a soluble product in DMSO electrolyte. The nature of this material does not depend on the stereochemistry of the starting complex and its characterization, either as a solid and in solution, has been investigated by an interplay between electro analytical and spectroscopic techniques including H-1-NMR, UV-vis, MS and IR. It appears from the data that one of the possible structure of the material is an oligomeric [Ru(terpy)(CO)](n) with n = 3. The trans- and cis -[Ru(terpy)(CO)Cl-2] complexes and the related organometallic metal-metal based material display catalytic activity in the electroreduction of carbon dioxide in hydro-organic media. Interestingly, [Ru(terpy)(CO)](n) modified electrodes also display electrocatalytic activity in purely aqueous solutions.