Electronic spectroscopic data are reported for Co^I, Co^II, and Co^III mononuclear tetra(neopentoxy)-phthalocyaninate(2–)(L¹) and bridged binuclear tri(neopentoxy)phthalocyaninate(2–) species in solution and film phases. Electrochemical data show that the [Co^IIL¹] species cannot exist in a non-co-ordinating or weakly co-ordinating solvent containing hydroxide ion. Such solutions cause disproportionation of [Co^IIL¹] to a 1 : 1 mixture of [Co^IL¹]^– and [Co^IIIL¹]⁺(axial ligands omitted). The detailed electrochemistry of this system is explored. The chemistry of these two oxidation states towards heat, light, acids, bases, carbonate and sulphite ion are briefly reported for solution and film phases. The degree of intermolecular electronic coupling which occurs either through space, through the bridge, or directly in cofacial conformers is discussed in terms of the nature of the bridge of the binuclear species and oxidation state of the cobalt.