A composition useful for catalyzing alkylation and transalkylation reactions comprises a molecular sieve having alkylation and/or transalkylation activity, an inorganic refractory oxide component and greater than 3.5 weight percent water. Such a catalyst has been found to maintain a long life when used to produce ethylbenzene in an integrated process in which benzene is alkylated with ethylene and transalkylated with diethylbenzene. The catalyst can also be used to produce cumene via an integrated process in which benzene is alkylated with propylene and transalkylated with diisopropylbenzene.