Polybenzimidazole (PBI) was first polymerized by scientists in the 1950s. In 1961, aromatic PBIs with exceptional thermal and oxidative stability were synthesized by H. Vogel and C. S. Marvel. Subsequently, Hoechst Celanese Corp. (then Celanese Corp.) because involved in PBI research through contracts with NASA and the Air Force Materials Laboratory. The company developed polymerization and fiber-spinning technology for a high- temperature resistant PBI fiber in 1963. In 1967, after a fire aboard the Apollo spacecraft, NASA initiated programs with Hoechst Celanese to develop protective clothing made from PBI fiber. PBI was used in a variety of applications for the U.S. space program, including flight suits and other protective clothing, webbings, straps, and tethers. Research in raw materials and process development continued, along with applications development, during the 1960s and 70s.

In 1983, Hoechst Celanese began commercial production of PB1 fiber. Today, PBI fiber has been used successfully in firefighters' gear, industrial protective clothing, fire-blocking layers for aircraft seats, braided pump packings, and other high-performance products. Research has continued to develop other forms of PBI. In addition to Celazole molded parts, these forms include polymer additives, films, fibrids, papers, microporous resin, sizing, and coatings.

Hoechst Celanese scientists say the material has no known melting point and can withstand pressures of up to 58,000 psi. It also has demonstrated resistance to steam at 650°F. Hoechst AG is the only producer of tetraaminobiphenyl, the essential raw material used in making PBI resin.