A series of Ir/ZrO2-MoO3 catalysts with different molybdenum concentrations and iridium loadings were synthesized and studied for ring opening of methylcyclopentane and cyclohexane to n-hexane. X-ray photoelectron spectroscopy (XPS) indicated that molybdenum and zirconium were present mainly in the form of MoO3 and ZrO2, respectively, and temperature programmed desorption (TPD) indicated the acidity was strongly correlated to the MoO3 content. Iridium was incorporated by wet impregnation to a desired loading of 30 and 300 ppmw with the concentration verified by instrumental neutron activation analysis (INAA). The vapor phase conversion of methylcyclopentane and the liquid phase conversion of cyclohexane were subsequently studied to determine catalytic activity and selectivity. The Ir/ZrO2-MoO3 catalyst with 3.5 at.% molybdenum and 30 ppmw iridium produced an overall relatively high activity and selectivity for the conversion of cyclohexane to n-hexane.