The isobutane/butene alkylation catalyzed by H2SO4 is a liquid/liquid reaction, and the limited solubility of the hydrocarbon in the catalyst inhibits mass transfer, leading to occurrence of side reactions. Amphiphilic surfactant could enhance mass transfer in multiphasic systems. In this study, a series of quaternary ammonium and phosphonium surfactants were used as the additive to enhance the catalytic performance of H2SO4 for isobutane/butene alkylation. Ammonium surfactants showed much better activity to improve product distribution than the phosphonium one. The enhanced product distribution and alkylate quality were attributed to the well dispersion of the hydrocarbon in the acid and increased hydrocarbon solubility in the catalytic system, i.e., enhanced mass transfer in the reaction system. The reaction parameters were optimized, and under these conditions, weight percentage of C8 in the product was 87.5%, and research octane number (RON) of the alkylate could reach 97.8. Lifetime of the surfactant/H2SO4 system was 130 times compared with 51 times for the system with no additive due to inhibition of the formation of acid soluble oil (i.e., products of side reactions). This proposed catalytic system with the ammonium surfactant as the additive is promising to be employed in industrial C4 alkylation process. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.