A petroleum desalting process in which the oil/water emulsion layer which forms in the desalter vessel between the settled water layer and the settled oil layer is separated into the oil and water components by contact with a heated high boiling hydrocarbon to break the emulsion and vaporize water from the emulsion in a flash drum. The vessel has an emulsion outlet for removing an emulsion stream from the emulsion layer and a conduit connecting the emulsion withdrawal port to an inlet of an optional settling drum to effect and initial separation into an oil-enriched phase and a water phase with the oil-enriched phase led to the flash drum.