Reports of the criminal first surfaced in June 2014, when a 17-year-old girl filed a report saying the suspect came up behind her and set her hair on fire with a lighter as she was waiting for the train in the Zoologischer Garten station.
Another victim came forward after police released stills from surveillance footage in December.
The 25-year-old told police the man fled while she was extinguishing flames in her hair after an attack at Ostbahnhof train station.
Police are looking for witnesses to both incidents, or anyone who could help identify the suspect.
He is a man between 18 and 25 years old, with a lean, athletic figure, with dark, cropped hair shaved around the sides and back of his head.
Contacted by The Local on Friday, a Berlin police spokesman said that the attacks appeared to be random, with no details linking the two young women.