Cape Town trains were delayed on Monday morning because of a bomb scare at Maitland station, Metrorail said.
Regional manager Mthuthuzeli Swart said it received a "tip-off" around 6am and cleared the station to allow police to inspect the railway tracks.
Explosives officers found nothing and train services resumed at 7.15am.
Six trains experienced an average 20 minutes delay.
"We condemn the action in the strongest possible terms... these individuals thrive on causing chaos and must be stopped immediately," Swartz said.
A reward of up to R25,000 was on offer for information leading to the conviction of hoax callers.