The treatment of wastes is one of the most important concerns of modern society, and pyrolysis is claimed as an alternative method to improve the quality of the products obtained from materials of a hydrocarbon nature such as coal and residues from petroleum distillation. The main objectives of this paper are (i) to evaluate the interactions between coal and petroleum residues (PR) which lead to a synergetic effect on the production of light olefins C-1-C-4 and BTX and (ii) to study the influence of variables such as temperature, pressure, and coal nature on the intensity of these effects. The study has been carried out by pyrolysis/gas chromatography in a pyroprobe using two coals (Samca and Figaredo), a petroleum residue, and mixtures of them in a mass ratio (coal/residue) of 70/30. Two temperatures, 800-900 degrees C, and two pressures, 0.1-1 MPa, have been studied. Different results are obtained for the individual components and the mixtures depending on the nature of the coal. In general, an increase in temperature promotes the production of both light olefins and BTX and the synergetic effects desired from the copyrolysis of the mixtures. On the other hand, increasing the pressure does not favor, the production of light olefins.