Using the self-assembly technique, novel monolayers on gold have been prepared from new cobyrinate dialkyl disulphide derivatives. The Successful formation is proved by cyclic voltammetry and by in situ ellipsometry. The electrochemical characterisation by reductive desorption allows to estimate the surface coverage and reveals that the presence of two cobyrinates introduces some disorganisation in the monolayer. More packed and organised monolayers have been observed in systems containing only one terminal redox centre. From ellipsometric measurements a possible orientation of the cobyrinate centre in the adsorbed monolayer is modelled. The modified electrodes display electrocatalytic activity for the reduction of dissolved oxygen.