Proton conduction in novel anhydrous membranes based on host polymer, poly(4-vinylbenzylboronic acid), (P4VBBA) and phosphoric acid, (H 3 PO 4 ) as proton solvent was studied. The materials were prepared by the insertion of the proton solvent into P4VBBA at different stoichiometric ratios to get P4VBBA·xH 3 PO 4 composite electrolytes. Homopolymer and the composite materials were characterized by FT-IR, 11 B MAS NMR and 31 P MAS NMR. 11 B MAS NMR results suggested that acid doping favors or leads to a four-coordinated boron arrangement. 31 P MAS NMR results illustrated the immobilization of phosphoric acid to the polymer through condensation with boron functional groups (B–O–P and/or B–O–P–O–B). Thermogravimetric analysis (TGA) showed that the condensation of composite materials starts approximately at 140°C. An exponential weight loss above this temperature was attributed to intermolecular condensation of acidic units forming cross-linked polymer. The insertion of phosphoric acid into the matrix softened the materials shifting T g to lower temperatures. The temperature dependence of the proton conductivity was modeled with Arrhenius relation. P4VBBA·2H 3 PO 4 has a maximum proton conductivity of 0.0013S/cm at RT and 0.005S/cm at 80°C.