An optical composite material comprises an amorphous optical material (6) with a first refractive index (na), into which crystalline nanoparticles (7) having a second, higher refractive index (nn) are embedded, wherein the amorphous material (6) and the nanoparticles (7) are resistant to UV radiation. A microlithography projection exposure apparatus comprises a projection objective (2) with at least one optical element (3) which is, in particular, operated in transmission and consists of an optical composite material of this type. In a method for producing the optical composite material, crystalline nanoparticles are introduced into the amorphous optical material during flame deposition in a soot or direct process.