[en] Self-assembled monolayers (SAMs) of the alkylthiols with [Os(bpy)₃]²⁺ moiety at the terminal position were prepared on gold electrode surface. Examination of the cyclic voltammograms for the SAM shows that it does not organize well unlike alkylthiols, which is attributed to the much larger diameter of [Os(bpy)₃]²⁺ moiety compared with the cross-section of alkyl chains and the distance between the adsorption sites. Eelctromicrogravimetry study shows that the hydration numbers of the electrolyte were 16±2, 11±1, 5±1 and 24±6 for ClO₄^-, PF₆^-, NO₃^-, and SO₄^2-, respectively. The binary SAMs of alkylthiols with [Os(bpy)₃]²⁺ terminal-group were prepared by co-adsorption of alkylthiols as spacer molecules, which results in better packing in SAM and accordingly the stability was enhanced