The invention relates to radiation-curable coating composition containing: a) 10 to 100 wt. % of a urethane (meth)acrylate which contains both (meth)acryloyl groups and free isocyanate groups, b) 0 to 90 wt. % of (meth)acrylates which contain (meth)acryloyl groups but no free isocyanate groups or any isocyanate-reactive groups, the wt. % under a) and b) adding up to 100 wt. %, based on the weight of a)+b), and c) 0 to 10 wt. %, based on the sum of components a) and b) of a UV initiator for free radical polymerization. The invention also relates to metal, plastic, film, wood, leather and mineral substrates coated with the above-mentioned radiation-curable coating composition.