We report on the synthesis and structural characterization of the cobalt pentanuclear helicate complex from the rigid tetradentate bis(2-pyridyl)-3,5-pyrazolate ligand bpp(-), namely, [{Co-II(mu-bpp)(3)}(2)Co-3(II)(mu(3)-OH)](3+) (1(3+)), in which a trinuclear {Co-3(II)(mu(3)-OH)} core is wrapped by two {Co-II(mu-bpp)(3)} units. The cyclic voltammogram of 1(3)+ in CH3CN revealed seven successive reversible one-electron waves, in the 0 and -3.0 V potential range, highlighting the remarkable stability of such architecture in several redox states. Two mixed-valent states of this complex, the two-electron-oxidized (Co3Co2III)-Co-II (1(5+)) and the one-electron-reduced species (CoCo4II)-Co-I (1(2+)), were generated by bulk electrolyses and successfully characterized by single-crystal X-ray diffraction among the eight redox levels between Co-5(I) and (Co3Co2III)-Co-II that can be accessed under electrochemical conditions. Because of the crystallographic characterization of 1(5+) and 1(2+), the five reduction processes located at E-1/2 values of -1.63 (1(3+/2+)), -1.88 (1(2+/+)), -2.14 (1(+/0)), -2.40 (1(0/-)), and -2.60 V (1(-/2-)) versus Ag/AgNO3 were unambiguously assigned to the successive reduction of each of the five Co(II) ions to Co(I), starting with the three ions located in the central core followed by the two apical ions. The two other redox events at E-1/2 values of -0.21 (1(4+/3+)) and -0.11 V (1(5+/4+)) are assigned to the successive oxidation of the apical Co(II) ions to Co(III). The Co(I) complexes are rare, and the stabilization of a Co(I) within a trinuclear mu-hydroxo core in the reduced species, 1(2+), 1(+), 1(0), 1(-), and 1(2-), is probably the result of the particular structure of this complex in the presence of the two apical sites that maintain the trinuclear core through the six bridging bpp(-) ligands. The spectroscopic characteristics of 1(2+), 1(3+), and 1(5+) (ultraviolet-visible and X-band electron paramagnetic resonance) are also described as well as their magnetic properties in the solid state.