Two signed works of art by Damien Hirst were taken from an upmarket gallery after a suspect stormed the building in Blenheim Crescent, Notting Hill, London, between 3am and 3.30am on Monday.
The burglar entered the gallery by forcing open the front doors and drove the items away in a dark-coloured hatchback-type vehicle towards Ladbroke Grove, the Metropolitan Police said.
The stolen pieces feature multi-coloured dots - the larger work is entitled Pyronin Y, which was created in 2005 and worth £15,000 and the other is called Oleoylsarcosine, which is valued at £18,000.
Detective Sergeant Jon Lightfoot, from Kensington and Chelsea Borough, said: "It appears the suspect has specifically targeted the two pieces.
"The items would have been visible in the back of the car and we are appealing for any witnesses or anyone with information to please come forward."