A process for converting gaseous alkanes to olefins, higher molecular weight hydrocarbons or mixtures thereof wherein a gaseous feed containing alkanes is thermally reacted with a dry bromine vapor to form alkyl bromides and hydrogen bromide. Poly-brominated alkanes present in the alkyl bromides are further reacted with methane over a suitable catalyst to form mono-brominated species. The mixture of alkyl bromides and hydrogen bromide is then reacted over a suitable catalyst at a temperature sufficient to form olefins, higher molecular weight hydrocarbons or mixtures thereof and hydrogen bromide. Various methods are disclosed to remove the hydrogen bromide from the higher molecular weight hydrocarbons, to generate bromine from the hydrogen bromide for use in the process, and to selectively form mono-brominated alkanes in the bromination step.