LAB (Linear Alkyl Benzene) isomers were obtained by the alkylation of benzene with 1-dodecene over FAU, BEA and EMT zeolites in the presence of decane as solvent. The initial activities were compared by fitting the kinetics early data with a pseudo first order law in dodecene. These were in agreement with those determined from the slope of the conversion versus time curve at zero conversion. The activity and stability were discussed in terms of the residual Na+ content, Si/Al ratio and porous structure of the catalysts. The selectivity to the most desired 2-phenyl dodecane isomer was found to increase with increased porous constraints. Yields in the preferred isomer over BEA catalysts were very close to those provided by the FAU open structure catalysts in spite of a much lower conversion over BEA catalysts. Deactivation affected not only the alkylation reaction, but the isomerisation of the olefin as well, over BEA catalysts.