Trioctylphosphine is an organophosphorus compound with the formula P(C8H17)3 sometimes abbreviated TOP.

Trioctylphosphine reacts with oxygen to form trioctylphosphine oxide.

For this reason it is usually handled with air-free techniques.

TOP reacts with elemental selenium to give trioctylphosphine selenide (TOPSe), which is a reagent for the preparation of cadmium selenide and related semiconductors.

This article about an organic compound is a stub.