Abstract: This disclosure relates to alkylation processes. The process involves providing two or more reaction zones disposed in sequence. In at least the first two reaction zones, olefin mixture comprising C3 and C4 olefins is contacted with isoparaffin comprising isobutane in the presence of sulfuric acid solution under effective alkylation conditions to produce a product mixture comprising spent acid solution and alkylate product, wherein the molar ratio of C3 to C4 olefins in the olefin mixture decreases in each subsequent reaction zone. In the process, the sulfuric acid solution present in a reaction zone contains the spent acid solution produced in the immediately preceding reaction zone.