The oxidative dehydrogenation of n-hexane over beta-NiMoO4 catalysts was performed in a fixed bed continuous flow reactor. Catalytic testing was done below and above the flammability limits for n-hexane and the effect of reaction conditions was examined to optimize hexene selectivity. The contact times (0.61-2.4 s), n-hexane/oxygen molar ratios and nitrogen dilution (31-60%) were varied. The highest selectivity to total hexenes obtained was 54.7% which was made up of 27.4% 1-hexene, 25.0% trans-2-hexene and 2.3% cis-2-hexene. These selectivities were obtained at a fuel/O-2 ratio of 2.2, a contact time of 1.0 s and 43% nitrogen dilution.