As the world’s transportation is seeking to switch towards renewable and sustainable sources of energy, the research in fuel cell technology has gained momentum. Proton exchange membrane fuel cell (PEMFC) operating at temperature range 100–200°C (high-temperature proton exchange membrane fuel cells, HT-PEMFCs) has gained interest in their major application to electric power generation. The most promising material is polybenzimidazoles (PBI). Synthesis methods such as condensation polymerization, solid-state or melt polymerization, etc. give the polymer with different inherent viscosity. The monomer modifications both in tetramine and the diacid, reveal variations in glass transition value. Further insight into the membrane casting solvents and methods along with its proton conductivity has been reviewed. Review paper is comprising of Part 1: for the synthesis methods, structural changes, and applications of PBIs in HT-PEMFCs while, Part 2: for the various kinds of PBIs has been discussed.[Formula: see text]