Efficient hydrogen evolution from decalin by heating at 210degreesC and cooling at 5degreesC was attempted in a batch-wise reactor by the use of "superheated liquid-film-type catalysis". When the carbon-supported metal catalyst 0.75 g was immersed with decalin 3.0 ml under a reactive distillation conditions, a liquid-film state was realized and the catalytic conversion of decalin was remarkably enhanced in contrast to the ordinary suspended state (e.g., 0.75 g/10 ml). Active sites in the liquid-film state were superheated, being higher in temperatures than the boiling point of the substrate solution, which gave the catalytic abilities of both high reaction rates and accelerated desorption of the reaction products from the catalyst surface, as evident from the Langmuir-type analysis. In addition, scarcity of substrate in the liquid-film state improved the utilization efficiency of heat by allotting it more to the endothermic reaction rather than to inevitable evaporation. According to our repetitive reaction test with the same catalyst, reproducible activities were confirmed well. The adoption of superheated liquid-flim-type catalysis for decalin dehydrogenation would make the reaction couple with naphthalene hydrogenation useful for mobile storage of hydrogen.