The remarkable stability of the tetrazole model compound in alkaline environment motivated us to explore this functionality as electrolyte uptake promoter in alkaline ion solvating membranes based on heteroatom free polymer backbones. As shown in Scheme 1, poly(styrene-co-acrylonitrile) (SAN) was converted to the to the corresponding 1H-tetrazole via a click-type [3+2] cycloaddition reaction. This methodology has previously been employed for the synthesis of poly(vinyl tetrazole)s from polyacrylonitrile for proton conducting blend membranes with sulfonated polystyrene. The degree of functionalization was defined by the content of acrylonitrile in the pristine polymer. Hereafter, SAN25 and SAN30 are used for SAN containing 25 and 30 wt% acrylonitrile, respectively. The corresponding tetrazolated polymers are referred to as STz25 and STz30.