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)Cl2] 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 electroanalytical and spectroscopic techniques including 1H-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)Cl2] 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.