Abstract: Molded bodies of thermoset material are produced from monomers, oligomers or higher pre-polymers of reactive resins by pressure reaction injection molding. The molded bodies may contain filler and/or reinforcing material. The process is carried out in a mold consisting of a first, preferably upper half mold and a second, preferably lower half mold, and an inlet socket opening downwardly into the first half mold. The mold is equipped with heating coils adapted for applying separately a lower temperature to the first half mold and a higher temperature to the second one. During the introduction and hardening phase of the reactive mixture, the first half mold is maintained at a lower temperature than the second half mold, the temperature difference amounts to about 40 to 180, and preferably 60 to 120 centigrades.