Abstract: Processing and apparatus are provided for upgrading the octane of a mixed hydrocarbon gasoline feedstock by an integrated adsorption-isomerization process which catalytically isomerizes normal paraffinic hydrocarbons and concentrates non-normals in a product stream, in both the reactor-lead and adsorber-lead configuration.The process includes passing an adsorber feed stream comprising hydrogen as well as hydrocarbons to an adsorbent bed to adsorb normal hydrocarbons. The hydrogen is preferably obtained from a hot hydrogen-containing process stream which is not cooled or separated into component parts prior to forming the adsorber feed. In some embodiments, the hot-hydrogen containing stream comes from reactor effluent and in others from desorption effluent.According to the invention, the only hydrogen which will require cooling and separation from a hydrocarbon component is that which is recycled for desorption. The invention provides improved energy efficiency and can reduce equipment size and complexity.