Actinium(III) fluoride, represented by the chemical formula AcF3, is a chemical compound containing actinium and fluorine. In this compound, actinium is in the +3 oxidation state, having lost three electrons, and fluorine is in the -1 oxidation state, having gained one electron.

Actinium is a rare, radioactive element, and its isotopes have limited practical applications due to its scarcity and radioactivity. Actinium-227, one of its isotopes, has been used as a neutron source and in radiation therapy for certain types of cancers.

Actinium(III) fluoride is not a compound that is commonly encountered, and its practical uses are limited due to the scarcity of actinium and its radioactive properties. Like other actinium compounds, proper safety measures and handling precautions are necessary when working with actinium(III) fluoride due to its radioactive nature. The primary significance of actinium(III) fluoride is in scientific research and studies related to actinium chemistry.