This paper represents the experimental data on a quantitative composition of cathode UO2-ZrO2 deposits, which are formed through simultaneous electrolytic reduction of UO22+ ions to UO2 and the exchange between the UO2 and Zr4+ ions present in the molten (NaCl-KCl)(equim.)-UO2Cl2-ZrCl4 electrolyte. A scheme for the formation of UO2-ZrO2 deposits containing up to 98 mol. % of ZrO2 is provided. The fraction of zirconium dioxide decreased as the ZrCl4 concentration decreased and as current density and electrolysis times increased. The electrolyte temperature influence on the average composition of the UO2-ZrO2 deposit was found to be insignificant. The structure of the cathode deposit was analyzed. The established regularities are explained by the change in the reduction and exchange reaction rates at the cathode. (C) 2013 Elsevier Ltd. All rights reserved.