This work concerns the development of hybrid organic/inorganic membranes from styrenic phosphonic polymers. The phosphonic charge, composed phosphonic polymers grafted onto silica nanoparticles, was obtained by grafting onto method. It consists of synthesizing first the polymer, and then the terminal functions of the latter react with silanol groups of silica. The phosphonated polymer was isolated in two steps, that is, an ATRP polymerization of 4-chloromethylstyrene followed by Mickaelis-Arbusov reaction. After the grafting onto silica, membranes are prepared through formulation containing the charge and the polymer matrix PVDF-HFP, which are dispersed in DMF. The acid form is obtained by hydrolysis in chlorydric acid. The membrane possessing a 40 wt % charge ratio (IEC = 1.08 meq g-1) was selected as reference. A proton conductivity of 65 mS cm-1 at 80 degrees C was measured in immersed conditions. When the membrane is no more immersed, the value decreases drastically (0.21 mS cm-1 at 120 degrees C and 25% RH). (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012