A new family of PEG-based SPEs containing potassium hydroxide and water was thoroughly investigated in order to better understand the structure of these materials and to relate it with the interesting conducting properties observed (ionic conductivity at room temperature between 5.10(-4) S/cm and 10(-3) S/cm). Several techniques were used, including DSC, TGA, X-ray diffraction and optical microscopy. This study revealed the presence of a crystalline complex depending on the composition of the SPEs. Despite great difficulties in performing the ac impedance technique with our systems, the conductivity vs temperature was investigated from room temperature to approximately 100 degrees C. The application of these SPEs to nickel secondary batteries (Ni/Cd and Ni/Zn) was also studied. Some results in terms of cyclability and improvement of the behaviour of the zinc electrode are presented.