Here we report the synthesis, electrochemistry and electrocatalytic activity of Fe-2(CO)(6)(mu-SC6F5)(2) (1) where the highly fluorinated bridge is electron-withdrawing, resulting in decreased electron-density at the iron iron bond. Additionally we discuss the related substituted complexes Fe-2(CO)(5)(PPh3) (mu-SC6F5)(2) (2) and Fe-2(CO)(4)(mu-Ph2PCH2PPh2)(mu-SC6F5)(2) (3). As none of the complexes could be protonated in their neutral form it was found that proton reduction catalysis in the presence of strong acid (HBF4) took place at the potential of the first reduction of complex I and 3, following an EC mechanism. Complex 2 was unstable in the presence of strong acid. For 1 the potential at which proton reduction took place represented a relatively mild reduction potential (-1.15 V vs. Fc/Fc(+) in acetonitrile) that was comparable to examples of similar complexes in the literature. Complex 1 generated a small concentration of a highly catalytic species after electrochemical reduction, which we attribute to cleavage of the Fe-Fe bond and formation of a mono-nuclear iron species or to Fe-S bond breakage generating a vacant coordination site. The contributions to the catalytic currents were simulated using DigiSim, where it was found that the rate limiting step for 3 was the elimination of H-2. It was also found that the highly catalytic species generated after reduction of 1 was more basic than 1(-) and also that protonation of this species was faster. (C) 2013 The Authors. Published by Elsevier B.V. All rights reserved.