AbstractThe thermal reaction of equimolar quantities of isophthalonitrile ando‐carborane has been shown to produce an adduct oligomer of isophthalonitrile. The structure was determined to involve condensation of three to five isophthalonitrile molecules to form a triazine‐type system. This type of bonding gave rise to a trimer and pentamer. Further, the reaction was a homogeneous liquid phase reaction in whicho‐carborane is involved in a catalytic manner in the oligomerization. The overall reaction has first‐order kinetics with an activation energy of 32.2 kc