This invention relates to Process for multilayer coating of substrates, comprising the steps: I) applying a layer of a water-based color-imparting and/or special effect-imparting base coat coating composition to a substrate, II) applying a layer of a clear coat coating composition curable by means of high energy radiation and optionally curable by at least one additional chemical curing reaction, and III) curing said clear coat layer by exposing it to high energy radiation, wherein the clear coat coating composition comprises: A) at least one compound capable of free-radical polymerization having at least one olefinically unsaturated group, B) at least one photoinitiator and C) at least one organic phosphine derivative.