This work deals with the cross-linking of polynorbornene-derivatives, utilizing the thiol-ene reaction for photolithographic patterning. The thiol-ene reaction is a well-known reaction of thiols and alkenes, which leads to the formation of thioethers. This reaction proceeds via a radical mechanism and can be induced photochemically. The addition reaction of multifunctional thiols to the double bonds of the polynorbornene in the backbone then leads to a cross-linking of the polymer chains. Poly((±)endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid dimethyl ester) (PNDME) and poly((±)endo,exo-bicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic acid diphenyl ester) (PNDPE) were synthesized, using the ring-opening metathesis polymerisation. Reactive coatings containing polymer, multifunctional thiol and various photoinitiators were prepared. The cross-linking reaction of the coatings was investigated with IR-spectroscopy. Photolithographic structuring of PNDME on a mask aligner yielded high-contrast structures. Moreover, three-dimensional objects with resolutions of several micrometers were achieved by two-photon lithography, using an appropriate photoinitiator. Also PNDPE was cross-linked via the thiol-ene reaction with wavelengths above 300 nm. The illumination of PNDPE with UV-light with a wavelength of 254 nm additionally leads to the photo-Fries reaction, which is a photoinduced rearrangement of arylesters to give hydroxyketones. With this reaction it was possible to tune the surface properties of the illuminated areas of thin PNDPE-films.