This invention relates to a process for (a) catalytically dehydrogenating a saturated hydrocarbon to the corresponding unsaturated hydrocarbon and hydrogen, (b) removing hydrogen from the products of step (a) over a catalyst supported on tin oxide and (c) dehydrogenating the products from step (b) under conditions of step (a). The process is effective for the production of e.g. styrene from ethylbenzene.