The reaction network for the oxidative dehydrogenation of n-butane to butadiene was examined. Delplots for experiments with n-butane, 1-butene, and 2-butene feeds were constructed. These analyses revealed that butadiene formed from both 1-butene and 2-butene. The experimental ratio of 2-butene and 1-butene was far from the equilibrium value, suggesting that the 2-butene to 1-butene equilibrium was not established, supporting the existence of the direct reaction of 2-butene to butadiene.