In order to understand the role of cobalt as electronic conductor additive into the nickel hydroxide electrode, cobalt oxyhydroxides were prepared by 'chimie douce' reactions from well-crystallised precursor phases. Depending on the synthesis conditions, two varieties were obtained, By analogy with the nickel hydroxide system, they were designated as beta(III)-HCoO2 and gamma-'HxCoO2'. The characterisation of the structure of the gamma-phase confirms the isotypy with the nickel phase. The structure of the beta(III)-HxCoO2 phases obtained by 'chimie douce' differs slightly from that of the homologous phase obtained by precipitation. The electric properties of these materials were also investigated. Due to the presence of 50% tetravalent cobalt, the gamma-phase exhibits a pseudo-metallic character, while the stoichiometric beta(III)-phase behaves as an insulator. The proton deficient beta(III)-HxCoO2 phase exhibits an intermediate behaviour.