A filled ionomeric membrane was achieved by dispersing phosphatoantimonic acid H3Sb3P2014, ×H20 (H3) in a Sulfonated PolySulfone (SPS) solution [1]. Water up-take is higher for filled than unfilled membrane as well as Protonic conductivity which is larger than that expected from the overall calculated concentration in charge carriers : a conductivity value of 0.135 S.cm−1 was gained at 50°C under 1003% Relative Humidity (HR) for a 1.6 meq.g−1 cationic exchange capacity (cec) SPS filled with 8% in H3 against 0.06S.cm−1 for an unfilled one. Mechanical measurements on the wet membrane shows the plasticizing effect of sulfonation, water and of the filler content which simultanously reinforced the cohesion of the membrane.