An easy experimental method to measure the solubility of isobutane/alkenes in sulfuric acid is established. By addition of minor amounts of anionic, cationic or ampholytic surfactants, the solubility value of isobutane/alkenes changes; that also influences the yield pattern of sulfuric-acid catalyzed alkylation reaction. According to solubility parameters, some additives are evaluated to enhance the solubility ratios of isobutane/alkenes. This gives rise to an improvement of the higher selectivity to trimethylpentanes; the research octane number is between 100 and I 10 and the material is an excellent component of gasoline. These additives are applied to isopentane/alkenes alkylation reaction simultaneously. It was found that the quality of alkylate gets better, due to the obvious decrease of the yield of heavy end materials (C10+). These facts reveal the industrially practical of solubility parameter and additives. Meanwhile, the yield of trimethylpentane is related linearly with the solubility ratio of isobutane/alkenes. (C) 2003 Elsevier B.V. All rights reserved.