The objective of the present study is to define whether alkenes, formed during alkane dehydrocyclization, are reconverted to the alkane and to elucidate the role of alkanes in the dehydrocyclization mechanism. In a competitive conversion, an alkene is converted much more rapidly than n-octane (C8D18) The lack of H/D exchange indicates that the adsorption of the n-octane is essentially irreversible, whereas some H/D exchange in the added alkene suggests that alkene desorption does occur; however, the added alkene does not desorb as the alkane, in conformity with irreversible adsorption of the alkane. The results demonstrate that the addition of a labeled alkene cannot provide data to establish the validity of the sequential dehydrogenation reaction pathway.