The development of solid acid catalysts for alkylation is hindered by the lack of understanding of the elementary acid catalyzed processes. General features for acid catalysis and how they apply to alkylation over heteropolyacids were examined. Potential mechanisms that control the alkylation of isobutene with n-butene and the potential deactivation of HPA by the loss of water were studied. The computations provided some insights into the requirements for an active solid acid. This is an abstract of a paper presented at the 229th ACS National Meeting (San Diego, CA 3/13-17/2005).