Triisopropylphosphine is the tertiary phosphine with the formula P(CH(CH<sub>3</sub>)<sub>2</sub>)<sub>3</sub>. Commonly used as a ligand in organometallic chemistry, it is often abbreviated to Pi-Pr<sub>3</sub> or P<sup>i</sup>Pr<sub>3</sub>. This ligand is one of the most basic alkyl phosphines with a large ligand cone angle of 160.
Pi-Pr<sub>3</sub> is similar to the more frequently used tricyclohexylphosphine. The triisopropyl derivative however, is a liquid at room temperature and more soluble in hydrocarbons.