Unsaturated hydrocarbons may be prepared by subjecting dehydrogenatable hydrocarbon to dehydrogenation in the presence of a dehydrogenation catalyst. The effluent stream from this step, comprising unconverted hydrocarbons, dehydrogenated hydrocarbons, hydrogen and steam, may then be passed to a selective oxidation step in which the hydrogen is selectively oxidized in the presence of an oxygen-containing gas to the substantial exclusion of the oxidation of the hydrocarbons. The oxidation catalyst which is employed will comprise a Group VIII noble metal, a Group IVA metal and a Group IA or IIA metal composited on a metal oxide support. The metal oxide support such as alumina will possess a particular configuration such as a polylobular particle containing from 3 to about 8 lobes and having a ratio of exterior surface to catalyst volume greater than [4D+2L] in which D is the largest representative diameter and L is the length of the particle.