The thermal behaviour, ionic conductivity and electrochemical stability of two new gel electrolytes synthesised by gelling (433K, 5min) polyacrylonitryle (PAN) and poly(vinylidene fluoride) and hexafluoropropylene (PVDF-HHP) (KF2801) polymer matrixes in a solution of LiCF3SO3 in ethylene carbonate–γ-butyrolactone (EC–γBL) solvent mixture are reported. The high ionic conductivity obtained, together with the good electrochemical stability (the current onset is detected around 4.7V versus Li/Li+ for the PAN-based gel, and 4.5V versus Li/Li+ for the PVDF-HFP gel, make this membranes of definite interest for practical applications in lithium batteries and supercapacitors technology.