The present invention is directed to isocyanato isocyanurates prepared from diisocyanates which contain a sterically unhindered isocyanate group bound to a primary aliphatic carbon atom and a sterically hindered isocyanate group which is bound to a tertiary carbon atom forming part of a cycloaliphatic ring system, said diisocyanate having an NCO content of about 20 to 50% by weight. The present invention is further directed to a process for preparing these isocyanato isocyanurates by catalytic trimerization and the use of the isocyanato isocyanurates in a process for the production of polyisocyanate polyaddition products, preferably two-component polyurethane stoving lacquers.