The woman, along with a friend, was travelling in the Jamalpur Express and the accused allegedly molested her when the train was at Pakur railway station in Jharkhand, the GRP said.
The woman immediately raised an alarm, following which other passengers and the Railway Protection Force (RPF) personnel, who were on board, caught hold of the accused.
The RPF personnel handed over the accused to the GRP at Burdwan railway station in West Bengal. The woman, who was on her way to Howrah station, also got down at Burdwan and lodged a complaint against the accused with the GRP.
The accused was produced before a court here, which remanded him to a four-day judicial custody.