Co/H-ZSM5 catalyzes propane dehydrogenation and aromatization reactions. Initial product selectivities, product site-yields, and the 13 C content and distribution in the products of 2-13 C-propane show that propane undergoes two primary reactionssdehydrogenation to propene and H 2 and cracking to methane and ethene. Propene and ethene then form aromatics via oligomerization-cracking reactions and both ethene and propene hydrogenate to form ethane and propane, respectively, via both hydrogen transfer from coadsorbed intermediates and dissociative adsorption of H 2 . These reaction pathways resemble those occurring on H-ZSM5, but Co cations provide an alternate pathway for the removal of hydrogen atoms in adsorbed intermediates as H 2 . A kinetic model was used to describe experimental rates based on these observations and to obtain rate constants for individual reaction steps as a function of Co content and H 2 concentration. H 2 inhibits propane dehydrogenation to propene and alkene conversion to aromatics, and increases the rate and the rate constant for ethene hydrogenation. Rate constants were obtained for propane reactions on H-ZSM5 and Co/H-ZSM5 (Co/Al ) 0.05-0.22). Propane dehydrogenation (k 1 ), ethene hydrogenation (k 3 ), and alkene dehydrocyclization (k 4 ) rate constants increased with increasing Co/Al ratio, because Co cations catalyze both the recombinative desorption of H 2 and its microscopic reverse, the dissociative adsorption of H 2 . Co cations increase the reversibility of hydrogen adsorption-desorption steps, and in this manner, they increase the deuterium content in all products of C 3 H 8 -D 2 reactions. Propane cracking rate constants (k 2 ) were not influenced by Co cations, because cracking occurs on acid sites and its stoichiometry and mechanism do not require hydrogen.