Isobutane has been alkylated with light (C-3-C-5) olefins for many years to produce high-quality, clean-burning gasolines. Processes that will significantly reduce operating costs and also produce higher-quality gasolines are proposed. These recommendations are based on recent improved understanding of process fundamentals, including the complicated chemical steps and the physical steps between and near the two or more phases in the reactor. Processes using sulfuric acid can be modified to reduce acid consumption significantly. Several solid catalysts have recently been proposed. All exhibit rapid catalyst deactivation for reasons explained in this article.