Uranium monophosphide is a compound of uranium and phosphorus, synthesized from heating metal uranium and white phosphorus: 4 U + P 4 ⟶ ⟶ --> 4 UP {\displaystyle {\ce {4U + P4->4UP}}} It is a potential nuclear fuel.
In air, a thin glassy surface layer protects the compound from oxidation; over the course of months after synthesis, this layer develops a metallic sheen.