A new lithium salt, lithium bis(4-nitrophenyl)suIfonylimide ie (P-NO2C6H4SO2)(2)NLi (LiNPSI), has been synthesized. The thermal and conductivity behaviour of two types of polymer electrolytes prepared therefrom have been studied. An amorphous polyurethane network based on short poly(ethyleneoxide) (PEO) segments was first used as a solvent : the polymer electrolyte shows conductivities close to those obtained with (CF3SO2)(2)NLi at the same salt concentration. When high molecular weight PEO was the solid solvent, the polymer electrolyte shows the typical behaviour of a semicrystalline system at temperatures below 50 degrees C. Above this temperature the system becomes amorphous and the conductivity isotherms reveal a maximum for a salt concentration corresponding to O/Li;= 30 (2.10(-4) S/cm at 66 degrees C).