The purpose of this research work is to prepare and assess the catalytic performance of platinum (Pt) dealuminated mordenite for the of n-hexane, n-pentane and light naphtha isomerization. The Pt dealuminated mordenite was prepared by dealumination of commercial mordenite catalyst by refluxing using hydrochloric acid at 100 °C in various time durations (0.50, 1.0, and 3.0 h). The commercial as well as dealuminated mordenite catalysts were examined by X-ray diffraction analysis, X-ray fluorescence, N2 adsorption-desorption, Fourier-transform infrared spectroscopy, temperature-programmed desorption (NH3-TPD), scanning electron microscopy, and transmission electron microscopy with high resolutions XRD and BET surface area analysis. These afore mentioned studies confirm that the dealumination process exhibit an increasing the external surface area and improved the total acidity with retaining the structure of mordenite. The catalytic performance was investigated for the of n-hexane, n-pentane and light naphtha isomerization by varying factors such as, temperature, reaction pressure, hydrogen flow, hourly mass feed flow rate and catalyst mass. Among the catalysts, the dealuminated catalyst with SiO2/Al2O3 ratio of 40% exhibited highest conversion Pt–Cl–Al2O3 operate set the lowest temperature on and selectivity. The density functional theory (DFT) calculation implies that the activation free energy for isomerization of n-hexane varies with the position of interacting C–H bond with mordenite (Pt/Mordenite) cluster. Besides, the activation energy for the n-pentane isomerization is lesser than the n-hexane isomerization. © 2019