Oxidation of the square planar Rh(I) complex [Rh(SPS^Me)(PPh₃)] (SPS^Me = 1-methyl-1-P-2,6-bis(diphenylphosphinosulfide)-3,5-(bisphenyl)-phosphinine) (1) based on mixed SPS-pincer ligand with hexachloroethane yielded the Rh(III) dichloride complex [Rh(SPS^Me)(PPh₃)Cl₂] (2), which was structurally characterized. The homoleptic Rh(III) complex [Rh(SPS^Me)₂][Cl] (4) was obtained via the stoichiometric reaction of SPS^Me anion (3) with [Rh(tht)₃Cl₃] (tht = tetrahydrothiophene). Complex 4, which was characterized by X-ray diffraction, was also studied by cyclic voltammetry. Complex 4 can be reversibly reduced at E = −1.16 V (vs SCE) to give the neutral 19-electron Rh(II) complex [Rh(SPS^Me)₂] (5). Accordingly, complex 5 could be synthesized via chemical reduction of 4 with zinc dust. EPR spectra of complex 5 were obtained after electrochemical or chemical reduction of 4 in THF or CH₂Cl₂. Hyperfine interaction with two equivalent ³¹P nuclei was observed in liquid solution, while an additional coupling with a spin ¹/₂ nucleus, probably ¹⁰³Rh, was detected in frozen solution. The ³¹P couplings are consistent with DFT calculations that predict a drastic increase in the axial P−S bond lengths when reducing (SPS^Me)₂Rh(III). In the reduced complex, the unpaired electron is mainly localized in a rhodium d_z² orbital, consistent with the g-anisotropy measured at 100 K.