The vapor-phase alkylation of benzene with each of ethylene and propylene was carried out in a fixed-bed reactor by using two different macroreticular resin catalysts ; Amberlyst 15 and Amberlyst XN-1010. The reaction rates were shown to be correlated by the Rideal kinetics where the chemisorbed ethylene or propylene reacts with the absorbed benzene, and the activation energies of each alkylation were estimated. Water in the feed plays the role of inhibitor to the reaction, and it has been confirmed that the rate of propylation is faster than that of ethylation possibly due to the larger polarity of propylene and its corresponding easiness of permeation into the resin particle.