The accident occurred around 6:00pm when the car in which the three were travelling fell into a roadside ditch after being hit by the Chattogram-bound Subarna Express in the Nalchata area.
Abdur Rahim died on the spot.
His wife Diljuara Khanam (63) and their driver Soleman Mia, 32, of Barishal district, sustained injuries and were rushed to Kaliganj upazila health complex, from where they were shifted to Dhaka for better treatment, said Pradeep Kumar Saha, sub-inspector at Kaliganj police station.
The former DU professor and his wife were heading towards Dhaka's Mirpur in their private car from Tangail district when the accident occurred.
His body has been sent to Narsingdi General Hospital morgue for an autopsy, the police officer said.