The electrochemistry and spectroelectrochemistry of mononuclear chloro(phthalocyaninato)rhodium(III), ClRhIII-Pc, has been studied in the solution phase, at ambient and low temperature. Reduction leads to a rhodium(II) species, ClRh(II)Pc which is stable at low temperature, with reversible electrochemistry, but at ambient temperature dimerizes generating a rhodium-rhodium-bonded dinuclear species. This dinuclear species is oxidized at a much more positive potential than the mononuclear species. The complex electrochemical behavior of these species is shown to be due to the presence of three different dinuclear Rh-II species with zero, one, or two axially bound chloride ions whose detailed electrochemical properties are explored. Reduction of the dinuclear Rh(II)Pc species leads to a reversibly generated anion radical species.