The supporters subjected passengers on the Edinburgh Waverley to Cowdenbeath train as they travelled to Saturday’s match between Dunfermline and Hearts.
Passengers reported hearing sectarian chants and “unsavoury language” from the fans throughout the 45-minute journey, including songs about Neil Lennon and the Pope.
The supporters got off the train at Dunfermline Town and Dunfermline Queen Margaret stations for the match at East End Park.
Constable Stuart Cowan, the police officer in charge of the inquiry, said: “This lasted for the duration of the journey and we believe the travellers were under the influence of alcohol.
“We would appeal for any witnesses to come forward.”