Generators, tools and a laptop were stolen from metal containers and cabins at a construction site in Daventry.
Police believe two offenders broke into five containers and cabins at the site in Long March sometime between 1pm and 2pm on Thursday January 14.
They drove a car into the car park and loaded the items, before leaving through the main gates.
Anyone with any information can call Northamptonshire Police on 101. Alternatively, they can call the independent charity Crimestoppers anonymously on 0800 555 111.