Polybenzimidazole/phosphoric acid (PBI/PA) membranes are the only true anhydrous proton conducting systems showing a great promise for PEM fuel cells operating at medium temperature. Neat liquid PA has the highest intrinsic proton conductivity of any known substance. Furthermore it is known that the high conductivity of PA is not only strongly influenced by the water activity, but also strongly reduced upon the presence of basic additives or e.g. basic sites of the polymer in PBI/PA materials. This draws to the need for fundamental understanding of this interaction in order to improve the existing and develop new water-free proton conducting PEM fuel cell materials. By gradually increasing the complexity from PA/imidazole mixtures to PA/benzimidazole mixtures to simple PBI membranes consisting of polybenzimidazole monomers in head-to-tail arrangement AB-PBI, we would like to reveal the influence of both, chemical composition and mesostructure on the proton conductivity mechanisms in these systems. The combination of the MD-simulations, NMR and QENS, which probes the dynamicsof the global proton network on a local spatial scale, can provide valuable insights into these mechanisms.