Computer equipment in every school in North Yorkshire is to be branded with an anti-theft spray to fight a "classroom crime-wave".
The effects of the spray stay on clothes and the skin for weeks
SmartWater - an invisible spray which can only be seen in ultra-violet light - will be sprayed on every piece of computer equipment in schools.
North Yorkshire County Council has invested £27,000 in the scheme.
Police said thefts were increasing and £187,265 of ICT equipment was stolen from the county's schools in 2005-6.
It is hoped the initiative will deter thieves and vandals during the school holidays.
County Cllr John Watson said there had been a 250% increase in the theft of ICT school equipment over the past two years.
He said: "Very little of the ICT equipment is ever recovered. We are now working in partnership with North Yorkshire Police to reduce crimes on site."
The use of SmartWater has already cut crime in many parts of Britain, the authority said.