Cis-5-Norbornene-exo-2,3-dicarboxylic anhydride is a bicyclic anhydride monomer. Its structure features a rigid norbornane skeleton with an exo-oriented anhydride functional group, which is highly reactive towards nucleophiles such as amines and alcohols. This compound is primarily used as a key precursor in the synthesis of high-performance polymers, particularly epoxy resins and polyimides. The rigid, bicyclic structure of the norbornane unit imparts excellent thermal stability, high glass transition temperature (Tg), and improved mechanical properties to the resulting polymers. These materials find applications in advanced composites, electronic encapsulants, and high-temperature adhesives. As a reactive building block, it is also employed in organic synthesis to introduce the rigid norbornane framework into more complex molecules, serving as a valuable intermediate for materials science research.