A study has been made of the activity of iron sulphide (pyrite) treated at increased hydrogen pressure. It has been shown that the pyrrhotine produced is formed directly as a catalyst and takes part in hydrogenation. The influence of the hydrogenation of pyrite on the production of liquid products from coal tar has been studied, and tests have been carried out on the catalytic activity of pyrite and the pyrrhotine specimens obtained with the aid of polycyclic compounds of anthracene and diphenylmethane in hydrogen.