A process simulator was developed to afford a better understanding of the performance of a butene-isobutane alkylation plant that uses a three-phase spouted bed reactor and a super acid solid catalyst. The mass and energy balances were numerically solved using lump of reactions and kinetic expressions previously developed. The results indicate the strong influence of the gas linear velocity and temperature in the riser and downcomer behavior that affects the activity, selectivity, and stability of the catalytic systems that cannot be predicted otherwise. The optimal operating conditions were determined for a particular catalyst and set of costs. The impacts of the recycling alkylate and isobutane to the reactor as well as the presence of hydrogen to control the coke formation are analyzed. (C) 2006 Elsevier Ltd. All rights reserved.