Hydrocracking reactions of naphthalene were investigated in a slurry-type reactor with different catalyst compositions consisting of iron-based compounds, metal oxides, and elementary sulfur in order to evaluate the most efficient catalyst composition. The reactions were repeated with the optimal catalyst composition at different H-2 initial pressures, temperatures, and holding times to determine the influence of these parameters. At the end of each reaction, liquid samples were analyzed by gas chromatography and mass spectrometry. The most effective catalyst composition for hyrocracking reaction of naphthalene was found to be a mixture of FeSO4 center dot H2O, Fe2O3, Al2O3, and sulfur. It can be concluded that hydrogenation, isomerization, cracking, and dealkylation take place during the hydrocracking reaction of naphthalene.