Abstract: The dehydrogenation of tetralin over Ni-Mo/Al2O3, Fe2O3/Al2O3, Fe2O3 and FeS2 has been shown in this investigation to be a typical consecutive reversible reaction, with a small amount of 1, 2-dihydronaphthalene as an intermediate. On the less-active catalyst Fe2O3, a trace of 1, 4-dihydronaphthalene (DHN) is also formed-the more active the catalyst, the lower the concentration of DHN. The rate of dehydrogenation rises with an increase of the partial pressure of tetralin, and declines with an increase of the partial pressure of hydrogen. It was observed that DHN is much more active than tetralin and naphthalene, and in the presence of a catalyst, it can be converted rapidly into naphthalene and tetralin. The fact that hydrogen can accelerate the hydrogenation of DHN is thought to be the main reason for its inhibiting action on the dehydrogenation of tetralin. In the presence of a catalyst, 1,4-DHN is unstable and can be isomerized into 1,2-DHN very quickly. The different catalysts studied have almost the same order of activity for dehydrogenation of tetralin, conversion of DHN and hydrogenation of naphthalene. On the hypothesis that the reaction is a consecutive one on the catalyst surface and that the adsorbed DHN is a very active intermediate, a reaction model was deduced. The equilibrium constants of adsorption and the rate constants of the catalytic reaction were calculated. The curves so calculated fit very well the experimental data, thus showing the validity of this model. Certain experimental results were explained in the light of this model and the related parameters.