Photoactivatable coating composition comprising at least one photoinitiator and a base-catalysed polymerisable or curable organic material comprising at least one polyisocyanate and at least one compound containing isocyanate reactive groups, wherein the isocyanate reactive groups comprise at least one thiol group and the photoinitiator is a photolatent base. Preference is given to a coating composition wherein the photolatent base is selected from the group of N-substituted 4-(ortho-nitrophenyl) dihydropyridine, a quaternary organo-boron photoinitiator, and an &agr;-amino acetophenone. The composition additionally may comprise an organic acid, a metal complex and/or a metal salt as a cocatalyst and/or a sensitiser selected from the group of thioxanthones, oxazines, rhodamines, and preferably from the group of benzo-phenone and derivatives thereof.