Cab charge dockets, EFTPOS machines and loose change have been stolen from taxis parked in Lalor and Thomastown over the last two months.
Police said seven taxis were broken into between March 16 and May 8, with the thefts all occurring in the late evening or overnight.
The taxis were parked in Roberts and Howell streets in Lalor and Mt View Road, Clarke Street, Stella Drive, and Alexander Avenue in Thomastown.
Police said the offender smashed the windows of the taxis to gain entry.
Whittlesea Crime Investigation Unit detectives have released an image of a man they believe can help with their enquiries.
Anyone with information is asked to contact Crime Stoppers on 1800 333 000.
