The incident occurred at around 1.30 AM when the woman, working as a reporter with a Hindi daily, was heading to her Dombivali home in neighbouring Thane district after winding up her work in Mumbai, railway police said.
She was travelling in the Karjat-bound suburban train when the robber, aged around 30, suddenly got into the ladies' compartment at Kalwa railway station.
As soon as the train started moving, he tried to overpower her in a bid to snatch her phone, police said.
After threatening the victim with dire consequences, the attacker jumped from the slow moving train on to the platform and fled, police said quoting the victim's complaint.
The shocked victim subsequently went home and approached the Thane railway police this morning.
An FIR has been registered on charges of molestation, criminal intimidation and robbery and a manhunt has been launched to nab the culprit, Thane Government Railway Police Inspector Anant Rane said.
A delegation of journalists was also present at the police station to express their solidarity.
