Pentaphenylphosphorus is an organic phosphorane containing five phenyl groups connected to a central phosphorus atom.

[4] Pentaphenyl phosphorus can also crystallise with solvent, (to form a solvate) with tetrahydrofuran and cyclohexane.

[2] Pentaphenylphosphorus reacts with acidic hydrogen to yield the tetraphenylphosphonium ion and benzene.

This is probably because tetraphenylbismuth halides (Ph4BiF, Ph4BiCl, Ph4BiBr) spontaneously decompose as the halogen reacts with one phenyl group.

[8] When heated with carbon dioxide or sulfur, bicyclic compounds are formed, where the reactant bridges between one of the phenyl groups and the phosphorus.