A process for the production of alkylbenzene includes the steps of introducing benzene and an olefin feed into a first alkylation reaction zone in the presence of a first alkylation catalyst under first alkylation reaction conditions to produce alkylbenzene and a vapor containing unconverted olefin; absorbing the unconverted olefin into an aromatic stream containing benzene and alkylbenzene; and, introducing the aromatic stream containing absorbed olefin into a second alkylation reaction zone containing a second alkylation catalyst under second alkylation reaction conditions to convert the absorbed olefin and at least some of the benzene of the aromatic stream to alkylbenzene. The process is particularly advantageous for the alkylation of benzene with ethylene to produce ethylbenzene. About 99.9% conversion of ethylene is achieved overall, with a substantial reduction in the required catalyst