In this work, a pyridine based polybenzimidazole (PPBI) is synthesized (I.V. 3.3 dL/g) from pyridine dicarboxylic acid and hydrochloride salt of diaminobenzidine. The polymer is characterized by FTIR and C-13 CP-MAS NMR. The resultant PPBI possesses high storage modulus of > 10GPa, tensile modulus of similar to 1 GPA and tensile strength of similar to 150 MPa. Amine functionalized silica nanoparticles in different degrees of amine grafting (LAC-low amine content/HAC-high amine content) are successfully incorporated into PPBI to result nanocomposite membranes. Both the neat PPBI and nanocomposites exhibit significant affinity towards phosphoric acid as indicated by the high acid uptake in short time (5 h). Proton conductivity of nanocomposites is increased by the addition of LAC/HAC nanoparticles (> 250 mS/cm at 140 degrees C). The HAC nanoparticle enriched nanocomposite (HAC 7) reveals self-assembly of amino-silica nanoparticles due to base-base repulsion (imidazole-amine). Hydrophobicity of nanocomposite membranes is increased with increase in LAC/HAC content which is attributed to the strengthening of hydrogen bonding between PPBI and nanoparticles. (C) 2018 Elsevier Ltd. All rights reserved.