A process for the catalytic alkylation of monocyclic aromatic compounds in a hydrocarbon process stream comprising contacting the monocyclic aromatic compound-containing hydrocarbon process stream with an alkylation agent under alkylation conditions with a mesoporous zeotype catalyst having an intracrystalline, non-crystallographic mesopore system and a mesopore volume of the zeotype crystals above 0.25 ml/g.