The work is realized in the frame of EDF R&D project devoted to innovative nuclear systems. This paper deals with the characteristics of fast reactor REBUS-3700 using molten salt fuel consisting of uranium and transuranics trichlorides dissolved in sodium chloride. A description of the system design. as well as a justification of its operating parameters is given. The performed neutronics studies demonstrate that REBUS-3700 gathers it positive breeding gain and strong negative salt expansion reactivity feedback. The safety analysis demonstrates all excellent reactor behavior with respect to the majority of single and combined unprotected events. The work also reveals the necessity to get more accurate nuclear data for the chlorine isotopes and to investigate the reactor configuration with radial fertile blanket. It seems also indispensable to realize more detailed thermo-hydraulic calculations and especially to perform a sizeable R&D program oil structure material capable to resist the corrosion induced by chlorides. (c) 2006 Elsevier Ltd. All rights reserved.