Upon treatment with sulfur hexafluoride, alkali metal diphenyl or dicyclohexyl phosphides are oxidized within seconds to tetraphenyl or tetracyclohexyl diphosphines. When bulky di-tert-butylphosphide is employed, fluorophosphine intermediates are detected. This is the first reported reaction of sulfur hexafluoride with metal phosphides, and a rare example of reactivity of sulfur hexafluoride at ambient temperature.