Polycondensation of 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTDA) with 3,3’-diaminobenzidine (DAB) and 3,3’4,4’-tetraaminodiphenyl ether (TADPE), respectively, in N,N’-dimethylacetamide (DMAc) at room temperature was found to produce high-viscosity polybenzimidazobenzophenanthroline (PBIPA) precursors. The PBIPA films, exhibiting excellent; thermal and mechanical properties, were conveniently prepared by the heat cure of precursors. UV-vis spectra and IR spectra of PBIPA were measured. The permeability to H-2, O-2, and N-2 of these two polymer membranes was determined at 30 degrees C and 1 atm.