Nuclear energy increasingly represents an important option for generating largely clean CO2-free electricity and zirconium is a fission product that is expected to be present in irradiated fuels. The present investigation addresses the electrochemical reduction of Zr4+ to Zr-o in LiCl - KCl eutectic molten salt in the temperature range 425-550 degrees C using cyclic voltammetry (CV), square-wave voltammetry (SWV) and bulk electrolysis. Simulations of the CV data indicate that the initial reduction proceeds through surface confined steps: Zr4+* + 2e(-) <-> Zr2+* and Zr2+* + 2e(-) <-> Zr* processes (*adsorbed species) followed by a peak-shaped complex diffusion controlled step that consists of a combination of closely spaced processes associated with the reactions Zr4+ + 4e(-) -> Zro and Zr4+ + 3e(-) -> Zr+*.Zr+*, probably in the form of ZrCl* is then further reduced to Zr-o* at even more negative potentials. The simulations provide the first quantitative analysis of the thermodynamics and kinetics of the Zr4+ reduction in the LiCl-KCl eutectic. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.016302jes] All rights reserved.