Transit authorities say the man sprayed "numerous" passengers on the Green Line trolley just before 2:30 p.m. on Saturday, March 9, at Lechmere station, MBTA police posted on X, formerly Twitter.
The man faces assault and battery with a dangerous weapon charges once arrested, police said.
The photo police released of the man shows him pointing the can of pepper spray at the photographer.
The man is pictured wearing a Boston Celtics hat, Nike shoes, a checkered scarf, and a black shirt and pants.
Transit police ask anyone with information on the man's identity to contact investigators at 617-222-1050.
Police did not speculate on a motive for the attack.
Click here to follow Daily Voice Cambridge and receive free news updates.