Seven exhaust parts were stolen from vans parked outside an Altham business.
The catalytic converters from seven vehicles were taken by thieves who broke into the premises of Cool Van on Moorfield Industrial Estate.
The incident happened between 6.30pm on Thursday, January 20 and 7.45am on Friday, Janaury 21.
Sgt Simon Holderness, of Accrington Police, is appealing for witnesses and said the value of the "specialist" parts were unknown.
Staff of Cool Van, refrigerated vehicle specialists, decided not to comment on the thefts.
Anyone with any information can contact Accrington Police on 01254 353042.