A polymerizable thermoset composition including a polymerizable organic cyanate ester resin and a polymerizable aryl ethynyl-terminated polyimide, a polymerized thermoset, a process for the production of the polymerized thermoset as well as the use of the polymerizable thermoset composition for the production of lightweight construction components, preferably carbon fiber composite materials (CFC), and a lightweight construction component, preferably carbon fiber composite material (CFC), containing the polymerized thermoset are described.