British Transport Police officers received the report about a train arriving at St Albans City station at around 5.20pm yesterday (November 17).
Officers carried out a search but did not find anything.
Train lines were closed between Luton and London St Pancras as the emergency services responded to the report.
This resulted in delays until around 9pm to Thameslink trains between these stations.
Lines have since reopened.
A BTP spokesperson said: “Officers were called at around 5.20pm on Monday (17 November) to reports of a suspicious item on a train arriving at St Albans railway station.
“Officers responded and conducted an extensive search, nothing was found.”
