SmartWater will mark every mile of track with a different code
Network Rail is treating trackside cable in the Midlands with SmartWater to beat copper wire thieves.
In the last year 462 trains across the region were cancelled and others delayed by 74,000 minutes because of cable thefts.
SmartWater has a chemical fingerprint that links to a crime scene and is only visible under ultra violet light.
The British Transport Police is also working with scrap dealers to prevent thieves selling on stolen cable.
Network Rail spokesman Keith Lumley said: "The world price of copper has gone through the roof and people are stealing cables to get at the copper core.
"In other industries where SmartWater has been used they've got a 100% conviction rate.
"We think that if criminals know that it will stop them from coming onto the railway."
The SmartWater company marks every mile of track with a differently coded batch, enabling police to pinpoint the exact location from where it came from.