We have studied the protonic conductivity of silica polymerized in situ within a poly(vinylidene fluoride)-co-hexafluoropropylene (PVDF-HFP) matrix. The macroscopic homogeneity of the membranes and the connectivity of the silica network strongly depend on the relative kinetics of inorganic condensation and PVDF drying. Upon base catalysis of the condensation reaction, the silica network forms faster than the organic polymer one. The conductivity linearly increases with the silica content, In contrast, acid conditions lead to slow kinetics of silica condensation that forms nanoclusters dispersed within a polymer matrix. The conductivity remains very low up to 30-35 wt.% of silica, then rapidly increases up to sigma similar to 5 X 10(-8) Omega (-1) cm(-1). Although these values remain very low, they allow to estimate the percolation threshold for the connectivity of the silica network, We report as well the growth of this network as inorganic filler in PVDF-co-HFP/SiO2/H3PO4 systems. Despite a loss of control in the inorganic polymer morphology, silica allows a better dispersion of H3PO4 in PVDF. The room temperature conductivity of these membranes becomes significant for some applications (sigma similar to 5 X 10(-3) Omega (-1) cm(-1)), remains stable for relative humidities between 20% and 90% while the water content does not drastically vary with water partial pressure.