The UV-vis and IR spectroelectrochemistry of W2(SBz)2(CO)82- (1) in 0.1 M (TBA)PF6/CH2C12 is reported (where SBz− = benzyl mercaptide). The reversible 2e− oxidation of W2(SBz)2(CO)82- is analyzed in terms of the individual le_ redox potentials, E°'-/2- and E°'O- by measuring the homogeneous disproportionation constant, Kdisp, of the electrochemically generated W2(SBz)2(CO)8~ radical. At 25 °C, we find Adisp equal to 7500 ± 4000. This value places E°'-/2- at a potential nearly 0.23 V positive of E°'0/- (E°'-/2- = -0.46 V; E°'0/- = 0.69 V vs aqueous AgCl/Ag). The reversal in positions of the le− redox potentials drives the disproportionation reaction and is rationalized to be a consequence of the electronic destabilization of W2(SBz)2(CO)8~ relative to W2(SBz)2(CO)82- and W2(SBz)2(CO)8.