Experimental information has been obtained on the formation and separation of dispersions of the two immiscible liquids, concentrated sulfuric acid and n-heptane. These dispersions have physical properties similar to those used in reactors to alkylate isobutane with C-3-C-5 olefins for the production of high-quality, clean-burning gasolines. The alkylation reactions occur at or at least near the liquid-liquid interface. Larger interfacial areas promote more rapid alkylation reactions and generally result in higher-quality products. Once the alkylation reactions are completed, however, rapid separation of the dispersion is needed to prevent undesired side reactions of isoparaffins and especially trimethylpentanes (having high octane numbers). The rates of separation of the dispersions were found to depend significantly on the temperature, the volumetric ratio of the two liquid phases, the composition of the acid, and the level of agitation employed to produce the dispersion. Several dispersions of hydrocarbon droplets in water were also investigated.