An examination has been made of the hydrodesulfurization (HDS) of thiophene over nickel mordenite. Catalysts were prepared by ion exchange procedures with the nickel exchanged directly for the initial sodium cation on the synthetic zeolite Norton sodium Zeolon 900 or in some instances with an intermediate exchange with an ammonium cation. The catalytic activities of these nickel mordenites for HDS of thiophene present at a level of 100 ppmw sulfur in a low sulfur naphtha at 300 °C and at 1 atm total pressure were determined in a continuous flow reactor. First order rate constants calculated from these test data demonstrated that mixed bed configurations exhibited an enhanced thiophene hydrogen desulfurization activity that was superior to that of either a commercial nickel-molybdena-alumina catalyst or a nickel mordenite when used alone. © 1979.