The electrolytic decomposition potential of ZnO has been studied in a solar furnace in the temperature range 1200-1675 K. The electrolyte consisted of various mixtures of CaF2 and Na3AlF6. The measured potentials were close to the thermodynamically predicted values for the reaction ZnO(s) → Zn(g) + 0.502(g). The zero current overvoltages, surprisingly, increased with increasing temperature and the concurrent change in composition. The specific conductances of the electrolytes were estimated in the temperature range 1200-1500 K. They increased with increasing temperature and the concurrent change in composition. Various materials were tested for use as electrodes and crucibles. Some of our experiences and our experimental techniques are described.