The solubility of thiophene + hydrocarbon mixtures in supercritical carbon dioxide was studied in this work. Phase behavior for the ternary system thiophene + pentane + carbon dioxide was measured at 333.66, 362.13, and 382.71 K. Additionally, behavior for the ternary system thiophene + octane + carbon dioxide was determined at 334.25, 363.73, and 383.28 K. Measurements were carried out to analyze the influence of pentane and octane on the solubility of thiophene in carbon dioxide. The results show that, for the system thiophene + pentane + carbon dioxide, the solubility of thiophene in carbon dioxide was higher than that obtained for the system thiophene + octane + carbon dioxide. The Peng-Robinson equation of state (PReos) using classical mixing rules was used to predict the experimental vapor-liquid equilibium (VLE) data of both ternary systems. The calculated values agree within an average absolute deviation < 10%.