A multi-step hydrocarbon conversion process for producing gasoline from propane or butane is disclosed. The feed hydrocarbon is passed into a dehydrogenation zone and the entire dehydrogenation zone effluent including hydrogen and light by-products is then passed into a catalytic condensation zone wherein the resulting olefins are converted into dimers and trimers. The condensation zone effluent stream is passed into a separation zone in which the dimers and trimers are concentrated into a product stream, with unconverted feed hydrocarbon and hydrogen being recycled to the dehydrogenation zone.