A series of carbon-based materials were illustrated to be efficient additives to improve the product distribution of isobutane/butene alkylation catalyzed by H2SO4. Among the tested materials, graphene oxide (GO) was shown to be the most efficient additive. With the presence of trace amounts (e.g., 0.1 wt %) of GO sheet, the weight percentage of C8 in the product could increase by similar to 11% and research octane number (RON) of the alkylate was enhanced by similar to 2. The presence of GO in H2SO4 led to no obvious change of the acidity. The improved product distribution could be attributed to the enhanced emulsification and better dispersion of the reactants in the acid. The lifetime of the catalytic system was extended from 110 times (with no additive) to 140 times, as the formation of acid soluble oil was inhibited when the additive was present. This efficient and environmentally benign emulsifier could be a particularly promising additive for the current alkylation process catalyzed by H2SO4.