The physical and chemical properties of chromium chlorides have been studied in fused NaCl-2CsCl eutectic at the temperature range 843-1008 K using an electrochemical cell containing a platinum-oxygen electrode with solid electrolyte membrane, which was used as pO(2-) indicator electrode. The concentration of oxygen ions in the solution was modifying by dropping the calculated amount of BaO. Titration of Cr3+ chlorocomplex by O2- ions demonstrated the precipitation of CrOCl and Cr2O3. The solubility constants of these compounds were calculated. E-pO(2-) and three-dimensional E-pO(2-)-T type diagrams, which summarized the properties of chromium species in the melt, were determined. (C) 2010 Elsevier Ltd. All rights reserved.