In this work, the effect of incorporating tungsten in HZSM-5 zeolites over the performance of desulfurization and octane enhancement processes of heavy naphtha was investigated. The physical and chemical characterization of the catalysts were analyzed by means of XRD, BET, NH3-TPD, TPR and XRF. The catalytic properties were determined at 5 barg, 450 degrees C, H-2/Oil = 150 Nml/ml and WHSV = 1 h(-1) inside a fixed bed reactor. The standard methods of detailed hydrocarbon analysis, gas chromatography, ASTM D-2699 and ASTM-D5453 were utilized to determine the liquid hydrocarbon compositions, detailed analyses of the off-gases, research octane number and the total amount of sulfur of the feed and products, respectively. The obtained results showed that the interaction between the Bronsted and Lewis acid sites for the W/HZSM-5 samples at low SiO2/Al2O3 ratios and consequently high acidity in the specific operating condition led to the parallel aromatization-desulfurization reactions to proceed perfectly. The total amount of sulfur decreased by 71 wt% for the SiO2/Al2O3 ratio of 20, and the aromatic component of the feed increased from 14.16 wt% to 72.82 wt% for the SiO2/Al2O3 ratio of 40; hence, RON raised from 52 to 98. Overall, by comparing the performance of the catalysts, it can be concluded that the best performance of simultaneous octane enhancement-desulfurization process was observed for the catalyst No_3, in which the amount of sulfur compounds decreased by 67.5% and the octane increased by 90%. (C) 2018 Elsevier B.V. All rights reserved.