Triphenylborane is a chemical compound with the chemical formula B(C₆H₅)₃, often abbreviated to BPh₃, where Ph is the phenyl group. It is a white crystalline solid and is both air and moisture sensitive, slowly forming benzene and triphenylboroxine. It is soluble in aromatic solvents.

The core of the compound, BC₃, has a trigonal planar structure. The phenyl groups are rotated at about a 30° angle from the core plane.

Even though triphenylborane and tris(pentafluorophenyl)borane are structurally similar, their Lewis acidity is not. BPh₃ is a weak Lewis acid while B(C₆F₅)₃ is a strong Lewis acid due to the electronegativity of the fluorine atoms. Other boron Lewis acids include BF₃ and BCl₃.

Triphenylborane was first synthesized in 1922. It is typically made with boron trifluoride diethyl etherate and the Grignard reagent, phenylmagnesium bromide.

Triphenylborane can also be synthesized on a smaller scale by the thermal decomposition of trimethylammonium tetraphenylborate.

Triphenylborane is made commercially by a process developed by Du Pont for use in its hydrocyanation of butadiene to adiponitrile, a nylon intermediate. Du Pont produces triphenylborane by reacting sodium metal, a haloaromatic (chlorobenzene), and a secondary alkyl borate ester.

Triphenylborane can be used to make triarylborane amine complexes, such as pyridine-triphenylborane. Triarylborane amine complexes are used as catalysts for the polymerization of acrylic esters.