5F may refer to:
5f electrons, of an electron configuration The Armageddon Factor (production code: 5F), a 1979 Doctor Who serial FlyOne (IATA code: 5F), a Moldovan low-cost airline Arctic Circle Air (former IATA code: 5F), a former US-American airline
See also 5-Fluoro-AMT (5-F-AMT) F5 (disambiguation)