A process is disclosed for the catalytic dehydrogenation of propane or butanes. The vapor phase reaction zone effluent stream is contacted with a heavy absorption liquid and then with a light absorption liquid. The light absorption liquid is composed of hydrocarbons recovered from the reaction zone effluent stream. This secondary contacting removes components of the heavy absorption liquid from the recycle gas, thus eliminating the deleterious effects of these compounds on the dehydrogenation catalyst. The heavy absorption liquid may be produced within the process by a catalytic olefin-consuming reaction zone.