This invention relates to a new catalyst for converting hydrocarbons. The catalyst comprises a platinum group component, a Group IVA component, especially tin, an alkali or alkaline earth component, more than 0.2 weight %, calculated on an elemental basis, of a halogen component and a porous carrier material, wherein the atomic ratio of the alkali or alkaline earth component to the platinum group component is more than 10. The catalyst is particularly useful for dehydrogenating paraffins having from 2 to 5 or more carbon atoms to the corresponding mono-olefins, or for dehydrogenating mono-olefins having from 3 to 5 or more carbon atoms to the corresponding di-olefins.