Among a large variety of innovative reactor concepts used to decarbonize industry, a French fast reactor using molten chloride salts as fuel and primary coolant has been developed with a CEA-Orano collaboration. The reactor operates at temperature up to 600 °C in which actinides (An) are homogeneously dissolved in the liquid phase containing alkaline and alkaline earth chlorides. To feed it, an essential step is to produce the NaCl-MgCl2-AnCl3 fuel salt system without impurities to avoid corrosion and precipitations issues. The main aim is to study a way of producing molten salt fuel with a high purity level (as low contaminants content as possible). The first step is to synthesize and characterize actinide chlorides by a multi-scale approach (XRD, SEM, TGA-DSC, WDS…). Actinide chlorides are hygroscopic and easily absorb moisture from the environment. The reference synthesis route is a gas-solid reaction by hydrochlorination of actinide oxalate. The investigation of other synthesis methods is also planned in order to obtain less hygroscopic material. Synthesized products will studied by electrochemistry after dissolution in the molten salt phase to determine actinides purity and contaminants nature and content. A purification process is used as the last step to remove most of impurities from the molten salt. Purification issues are impurity content determination and the definition of salt purity criterion. Some physicochemical properties measurements could be performed with purified salts.