Composite sPEEK membranes having different sulphonation degree were realised by using different percentages (0-20wt.%) of a functionalised silica (3-aminopropyl-functionalised silica) as a filler for vanadium redox batteries applications (VRBs). The prepared membranes were characterised in terms of Ion Exchange Capacity (IEC), vanadium up-take, proton conductivity, permeability and selectivity in order to select the best candidate for the selected application. The obtained data demonstrated good chemical-physical properties of the membranes realised and, moreover, a good selectivity and an increase of this parameter as a function of the filler percentage increase. Such parameter is the main aspect to be evaluated in order to select candidates for VRBs. In general, the good obatained results revealed a possible applicability of this membrane typology for VFRBs applications, avobe all if compared to similar membranes reported in literature using sPEEK polymer with a similar sulpohonation degree.